Aragón-Ortiz, Federico

Fink, Edwin

Nanne-Echandi, Clara I.

English

Universität München: Elektronischen Publikationen

Properties and N-terminal amino acid sequences of three 
Erythrina lectins from Costa Rica (Leguminosae) 
Federico Aragón-Ortiz1' Clara I. Nanne-Echandi' and Edwin Fink2. 
1 Departemente) de Bioquimica, Escuela de Medicina, Universidad de Costa Rica. 
2 Department of Clinical Chemistry and Clinical Biochemistry, Clinical Center City, LMU Nussbaumstrasse 20, D-8000 
Munich 2, Germany. 
Abstract: Three Erythrina lectins, from E. fusca, E. globocaliz and E. costaricensis were isolated by affinity chro-
matography. The lectins are glycoproteins with a monomelic molecular weight of 28 000. They agglutinate human 
erythrocytes irrespective of blood type and the activity was inhibited by N-acetyl-galactosamine, galactose and lactose. 
The N-terminal amino acid sequences of the three lectins were determined by automated Edman degradation of the 
native proteins. Comparison with the sequences of ten other legume lectins revealed extensive homology. The N-ter-
minal amino acid for E. fusca is Val, and Ala for E. globocaliz and E. costaricensis. 
Key words: Erythrina, legume, lectin, agglutination, N-terminal amino acid sequence. 
Erythrina is a family of deciduous legumi-
nous trees and shrubs widely spread in the trop-
ics and subtropics. Six species have been 
reported from Costa Rica: E. costaricensis, E. 
fusca, E. globocaliz, E. cristagalli, E. lanceola-
ta, and E. poeppigiana ( Flores and Rivera 
1984). Recently, a lectin from E. costaricensis 
was purified and characterized (Nanne-Echandi 
and Aragón-Ortiz 1991). Here we report the 
isolation of lectins from E. fusca and E. globo-
caliz by using affinity chromatography on lac-
tose-agarose column. The N-terminal amino 
acid sequences of these, and of the E. costari-
censis lectin, were determined. Comparison 
with the sequence of E. corallodendron lectin 
(Adar et al. 1989) reveals a high percentage of 
homology. 
MATERIAL AND METHODS 
Lactose-Agarose, CaCl2 , Tris-HCl, NaCl, 
lactose, glycine, sodium dodecylsulfate (SDS), 
Coomassie brilliant blue, Polyacrylamide, ace-
tone, carbohydrates, alcohols and proteins used 
as molecular weight markers were from Sigma 
(USA). 
Fresh mature seeds from E. fusca and E. 
globocaliz were obtained during the dry season 
of the year and crude extracts were prepared: 
80 g of dry seeds in each case were soaked in 
distilled water for 24 h at 5 °C and homoge-
nized in 1/2 L of 0.9% NaCl in a blender. The 
suspension was filtered and centrifuged at 
1 lOOOg. The clear supernatant was precipitated 
with four volumes of acetone, centrifuged and 
left at room temperature for 12 h. The acetone 
free precipitate was dissolved in three volumes 
of saline, centrifuged and the clear supernatant 
lyophilized and kept at -20 °C. 
One gram of each extract was suspended in 
8 mL of 0.01 M Tris/HCl +0.02 M CaCl2, pH 
7.2, centrifuged and the supernatant, adjusted 
to pH 7.2, applied to a 2 cm bed lactose-
Agarose column (1.2 x 10 cm). The column 
was eluted with the same buffer until the 
absorbance decreased to 0.03 units (OD=280 
nm). Volumes of 2.5 mL per tube were collect-
468 REVISTA DE BIOLOGIA TROPICAL 
ed and tested for agglutination of human RBC. 
Elution was continued with 0.2 M lactose con-
taining 0.15 M NaCl in the starting buffer. The 
lectin was pooled and thoroughly dialyzed 
against distilled water, concentrated by ultrafil-
tration using UM2 membrane and lyophilized. 
Polyacrylamide gel electrophoresis in Tris-
glycine, pH 8.4 was performed according to the 
method of Davis (1964). Staining was done 
with 0.05% Coomassie brilliant blue and with 
Schiff reagent for the detection of glycopro-
teins. PAGE in the presence of SDS was per-
formed according to the method of Laemmli 
(1970) in a 4 -30% (W/V) gradient gel . 
Automated N-terminal amino acid sequences 
analysis, was determined by Edman degrada-
tion (Edman and Beggl967) of the native pro-
te ins . A gas phase sequencer (Appl ied 
Biosystems, model 477A) connected to an on-
line HPLC 120A system for identification of 
the phenylthiohydantoin derivatives, was used. 
The agglutination assay was done according to 
Cumsky and Zusman (1979). Serial two fold 
dilution of 25 \iL aliquots of the isotonic lectin 
(200 |Lig/mL) were made in 25 |iL of Tris buffer 
(50 mM Tris/HCl, 150 mM NaCl, 40 mM 
CaCl2 , pH 7.0) containing 12.5 [iL of 2.5% 
erythrocytes in a microtiter V plate. The agglu-
tination was achieved using the following car-
bohydrates at a concentration of 0.1 M in 
buffered saline: D(+) galactose, D(+) glucose, 
D(+) mannose, D(-) fructose, D(+) xilose, lac-
tose, saccharose, N-acetyl-ß-D-galactosamine 
as well as with the alcohols mio-inositol and 
mannitol. 
RESULTS 
Affinity chromatography of 1 g of E. fusca 
extract on lactose-Agarose column is shown in 
Fig.l. The lectin was eluted with 0.2 M lactose 
peak (B). Agglutination of human RBC was 
observed with protein from tubes number 30 to 
35. Fig.2 shows PAGE at pH 8.4 of E. fusca 
lectin. Gel number 1 shows the crude extract 
stained with Coomassie brilliant blue. Gels 
number 2 and 3 show the purified lectin with 
only one protein band and the crude extract 
with several protein bands, both gels stained 
with Schiffreagent. Fig.3 shows SDS-PAGE of 
E. fusca and E. globocaliz lectins; both lectins 
show single protein bands corresponding to 
molecular weight of 28 000 for the monomelic 
form of the proteins (lanes 1 to 6). The multi-
meric forms of the lectin are observed in lanes 
7 to 12. The titer of the agglutination activity of 
E. fusca and E. globocaliz lectins is shown in 
Table 1, the inhibition of the agglutination 
activity in Table 2. The N-terminal amino acid 
sequence of the studied lectins compared with 
other Erythrina lectins is shown in Table 3. 
0.75 . 
E 
E 
o 
€0 
0.50. 
Û O 
0 .25 . 
0 . 00 
10 20 30 40 
TUBE NUMBER 
Fig. 1. Affinity chromatography of 1 g of E. fusca extract on 
lactose-Agarose column. Protein from peak A was eluted 
with 0.01M Tris/HCl + 0.02M CaC12, pH 7.2. Protein from 
peak B was obtained by elution with 0.2 M lactose + 0.15M 
NaCl. Agglutination of human RBC was observed with pro-
tein from tubes 30 to 35. Similar pattern of elution was 
obtained for the lectin from E. globocaliz and E. costaricen-
sis (data not shown). 
DISCUSSION 
It is inferred that the lectins from E. fusca 
and E. globocaliz are obtained as single band 
proteins, with a carbohydrate moiety. They are 
multimeric proteins and the molecular weight 
of the monomelic denatured protein was shown 
to be around 28 000. A similar staining behav-
iour and molecular weight was also reported 
for the lectin of E. costaricensis ( Nanne-
Echandi and Aragón-Ortiz 1991). The lectins 
did not differentiate between the human blood 
types studied. This activity was shown to be 
ARAGON & ORTIZ: Three Erythrina lectins 469 
Fig. 2. Polyacrylamide gel electrophoresis of E. fiàsca lectin. 
Gel 1 shows the crude extract stained with Coomassie bril-
liant blue. Gels 2 and 3 show the purified lectin and the 
crude extract both stained with Schiff reagent. 
Fig. 3. SDS-PAGE of the lectins from E. fusca and E. 
globocaliz.. (A) left lane : mol. wt standards (10 u,g each of 
the following proteins were applied: B. albumin, ovalbu-
min, carbonic anhydrase, PMSF trypsinogen and soybean 
trypsin inhibitor). Lanes 1 to 3 EFusL: Lanes 4 to 6 EGL in 
both cases; 10, 15 and 20 u,g of lectin were applied respec-
tively. (B) Left lane: mol. wt standards ( same as decribed 
above). Lanes 7 to 12 corresponds to EFusL and EGL in 
absence of SDS ; 10, 15 and 20 |ig of the lectins were 
applied respectively in each case. 
Table 2 
Inhibitory action of carbohydrates over the hemagglutinat-
ing activity of lectins from E. fusca and E. globocaliz 
toward human blood groups ABO, RhQ (D) 
positive and negative 
Blood group 
Inhibitor (0.1M) RhQ(D)+ Rh0(D)-
Table 1 
Titer of the agglutinating activity of the lectins from 
E. fusca and E.globocaliz, over the human blood groups 
ABO Rh0(D) positive and negative 
Blood group 
Lectin titer A B AB O 
1:2 
1:4 
1:8 
1:16 
+ + + 
+ + + 
+ + + 
A B AB O A B AB O 
Fucose + + + + + + + + 
Galactose 
Glucose + + + + + + + 
Mannose + + + + + + + + 
Fructose + + + + + + + + 
N-acetyl- + + + + + + + + 
mannosamine 
N-acetyl- - - - - - - - -
galactosamine 
Xylose + + + + + + + + 
Inositol + + + + + + + + 
Mannitol + + + + + + + + 
Lactose 
Saccharose + + + + + + + + 
470 REVISTA DE BIOLOGIA TROPICAL 
Table 3 
Comparison of the amino terminal sequences of the studied 
lectins with several known N-terminal sequences from 
other legume lectins 
EFusL V E T I S F N F S E F E P G N N D L T L Q G A A L I 
EGL A E T MS F S F S Q F Q P G N N D L T L Q G V 
ECosL A E T M S F S F 
ECorL V E T I S F S F S E F E P G N D N L T L Q G D S * P 
ECL V E T I S F S F S E F E P G N 
ECafL V E T I S F S F S E F E P G N 
EFL A E T I S F S F S E F E P G 
EHL V E T I S F S F S E F E P G N 
ELysL V E T I S F S F S E 
EPL V E T I S F S F S K F E A G 
EZL V E T I S F S F S E F E P G N 
P N A A E T V S F N F N S F S E G N 
SBA A E T VS F S WN K F V P K E 
* Leucine or isoleucine. Data from Lis et al. (1985) and 
Adar et al. (1989). 
The following abbreviated names for the Erythrina 
lectins are used: EFusL» E. fusca; EGL, E. globocaliz; 
ECosL, E. costaricensis; ECorL, E. corallodendron; 
ECL, E. cristagalli; ECafL, E. caffra; EFL, E.flabelli-
formis; EHL, E. humeana; ELysL, E. lysistemon; EPL, 
E. perrieri; EZLy E. zeyheri. For other legume lectins: 
PNA, peanut agglutinin; SBA, soybean agglutinin. 
inhibited by galactose, N-acetyl-galactosamine 
and lactose. 
A comparison of the N-terminal amino acid 
sequence of the lectins from E. fusca, E. globo-
caliz and E. costaricensis with the N-terminal 
sequences of other 10 lectins (Lis et al 1985) 
as well as with the amino acid sequence of E. 
corallodendron (Adar et al 1989), a high per-
centage of homology was observed, providing 
further evidence for the conservation of the 
lectin gene in legume plants. 
The lectins from E. fusca, E. globocaliz and 
from E. costaricensis (Nanne-Echandi and 
Aragón-Ortiz 1991), exhibi t many of the 
physicochemical properties already adscribed 
to other lectins characterized from the same 
family (Lis et al. 1985, Nanne-Echandi and 
Aragón-Ortiz 1991). All are glycoproteins with 
a neutral sugar content between 3-10%. After 
PAGE, they all give a positive reaction for car-
bohydrates with the Schiff reagent (Fig.l). The 
proteins are mulümeric with a monomelic mol-
ecular weight around 28 000. 
The agglutination of human RBC by E. 
fusca and E. globocaliz lectins as well as by E. 
costaricensis lect in (Nanne-Echandi and 
Aragón-Ortiz 1991), shows that these proteins 
behave similarly to ten other Erythrina lectins 
(Lis et al. 1985). They are unspecific in the 
agglutination of human RBC and the activity is 
inhibited by galactose, N-acetyl-galactosamine 
and lactose. These properties point out that the 
lectins bind to galactosyl receptors of the red 
cell membrane (Lis et al. 1985, Nanne-
Echandi-Aragón Ortiz 1991). 
ACKNOWLEGEMENTS 
The authors are grateful to Jorge Gomez 
Laurito, School of Biology University of Costa 
Rica, for his collaboration in the taxonomical 
identification of the Erythrina trees. Federico 
Aragón Ortiz is a research fellow of the Costa 
Rican Nat ional Counci l for Science and 
Technology (CONICIT), contract 897274-75 J. 
RESUMEN 
Très lectinas obtenidas de extractos crudos, 
preparados de semillas de la Erythrina fusca, E. 
globocaliz y E. costaricensis fueron aisladas 
utilizando cromatografia de afinidad. Las lecti-
nas son g l icopro te inas y en su forma 
monomérica presentan un peso molecular de 28 
000. Las lectinas aglutinan eritrocitos humanos, 
independientemente del grupo sanguineo. La 
actividad aglutinante es inhibida por N-acetil-
galactosamina, galactosa y lactosa. La secuen-
cia N-terminal de cada lectina fue determinada 
mediante la degradación automatizada de 
Edman. Al compararlas con las secuencias de 
diez lectinas de leguminosas, se encontre una 
extensa homologia. 
REFERENCES 
Adar , R., M. Richardson, H. Lis & N. 
Sharon. 1989. The amino acid sequence of 
Erythrina corallodendron lectin and its 
homology with other legume lectins. FEBS 
Lett. 257: 81-85. 
ARAGON & ORTIZ: Three Erythrina lectins 471 
Cumsky, M. & D. R. Zusman. 1979. Myxo 
bacterial hemagglutinin, a development spe-
cific lectin of Myxococcus xanthus. Proc. 
Nad. Acad. Sci. U.S.A. 76: 5506-5509. 
Davis, B. J. 1964. Disc electrophoresis 2. 
Method and application to human serum 
proteins. Ann. N. Y. Acad. Sci. 121: 404-
427. 
Edman, P. & Begg, G. 1967. A protein seque-
nator. Eurp. J. Biochem. 1: 80-91. 
Flores, E. M. & D. I. Rivera. 1984. Clave para 
semillas y plântulas de las especies del 
gènero Erythrina en el Valle Central, Costa 
Rica. Rev. Biol. Trop. 32: 241-252. 
Laemmli, U. K. 1970. Cleavage of structural 
proteins during the assembly of the head of 
the bacteriophage T4. Nature 227: 680-685. 
Lis. H., F. J. Joubert & N. Sharon. 1985. 
Isolation and properties of N-acetylgalac-
tosamine specific lec t ins from nine 
Erythrina species. Phytochemistry 24: 2803-
2809. 
Nanne-Echandi, C. I. & Aragón-Ortiz, F. 1991. 
Aislamiento, purificación y caracterización 
de una lect ina de la semil la del poro , 
Erythrina costaricensis. Rev. Biol. Trop. 39: 
15-21. 


Properties and N-Terminal amino acid sequences of three Erythrina lectins from Costa Rica (Leguminosae)

Open Access LMU ( Ludwig-Maximilians-Univ. München)

Properties and N-terminal amino acid sequences of three Erythrina lectins from Costa Rica (Leguminosae) Federico Aragón-Ortiz1' Clara I. Nanne-Echandi' and Edwin Fink2. 1 Departemente) de Bioquimica, Escuela de Medicina, Universidad de Costa Rica. 2 Department of Clinical Chemistry and Clinical Biochemistry, Clinical Center City, LMU Nussbaumstrasse 20, D-8000 Munich 2, Germany. Abstract: Three Erythrina lectins, from E. fusca, E. globocaliz and E. costaricensis were isolated by affinity chro-matography. The lectins are glycoproteins with a monomelic molecular weight of 28 000. They agglutinate human erythrocytes irrespective of blood type and the activity was inhibited by N-acetyl-galactosamine, galactose and lactose. The N-terminal amino acid sequences of the three lectins were determined by automated Edman degradation of the native proteins. Comparison with the sequences of ten other legume lectins revealed extensive homology. The N-ter-minal amino acid for E. fusca is Val, and Ala for E. globocaliz and E. costaricensis. Key words: Erythrina, legume, lectin, agglutination, N-terminal amino acid sequence. Erythrina is a family of deciduous legumi-nous trees and shrubs widely spread in the trop-ics and subtropics. Six species have been reported from Costa Rica: E. costaricensis, E. fusca, E. globocaliz, E. cristagalli, E. lanceola-ta, and E. poeppigiana ( Flores and Rivera 1984). Recently, a lectin from E. costaricensis was purified and characterized (Nanne-Echandi and Aragón-Ortiz 1991). Here we report the isolation of lectins from E. fusca and E. globo-caliz by using affinity chromatography on lac-tose-agarose column. The N-terminal amino acid sequences of these, and of the E. costari-censis lectin, were determined. Comparison with the sequence of E. corallodendron lectin (Adar et al. 1989) reveals a high percentage of homology. MATERIAL AND METHODS Lactose-Agarose, CaCl2 , Tris-HCl, NaCl, lactose, glycine, sodium dodecylsulfate (SDS), Coomassie brilliant blue, Polyacrylamide, ace-tone, carbohydrates, alcohols and proteins used as molecular weight markers were from Sigma (USA). Fresh mature seeds from E. fusca and E. globocaliz were obtained during the dry season of the year and crude extracts were prepared: 80 g of dry seeds in each case were soaked in distilled water for 24 h at 5 °C and homoge-nized in 1/2 L of 0.9% NaCl in a blender. The suspension was filtered and centrifuged at 1 lOOOg. The clear supernatant was precipitated with four volumes of acetone, centrifuged and left at room temperature for 12 h. The acetone free precipitate was dissolved in three volumes of saline, centrifuged and the clear supernatant lyophilized and kept at -20 °C. One gram of each extract was suspended in 8 mL of 0.01 M Tris/HCl +0.02 M CaCl2, pH 7.2, centrifuged and the supernatant, adjusted to pH 7.2, applied to a 2 cm bed lactose-Agarose column (1.2 x 10 cm). The column was eluted with the same buffer until the absorbance decreased to 0.03 units (OD=280 nm). Volumes of 2.5 mL per tube were collect-468 REVISTA DE BIOLOGIA TROPICAL ed and tested for agglutination of human RBC. Elution was continued with 0.2 M lactose con-taining 0.15 M NaCl in the starting buffer. The lectin was pooled and thoroughly dialyzed against distilled water, concentrated by ultrafil-tration using UM2 membrane and lyophilized. Polyacrylamide gel electrophoresis in Tris-glycine, pH 8.4 was performed according to the method of Davis (1964). Staining was done with 0.05% Coomassie brilliant blue and with Schiff reagent for the detection of glycopro-teins. PAGE in the presence of SDS was per-formed according to the method of Laemmli (1970) in a 4 -30% (W/V) gradient gel . Automated N-terminal amino acid sequences analysis, was determined by Edman degrada-tion (Edman and Beggl967) of the native pro-te ins . A gas phase sequencer (Appl ied Biosystems, model 477A) connected to an on-line HPLC 120A system for identification of the phenylthiohydantoin derivatives, was used. The agglutination assay was done according to Cumsky and Zusman (1979). Serial two fold dilution of 25 \iL aliquots of the isotonic lectin (200 |Lig/mL) were made in 25 |iL of Tris buffer (50 mM Tris/HCl, 150 mM NaCl, 40 mM CaCl2 , pH 7.0) containing 12.5 [iL of 2.5% erythrocytes in a microtiter V plate. The agglu-tination was achieved using the following car-bohydrates at a concentration of 0.1 M in buffered saline: D(+) galactose, D(+) glucose, D(+) mannose, D(-) fructose, D(+) xilose, lac-tose, saccharose, N-acetyl-ß-D-galactosamine as well as with the alcohols mio-inositol and mannitol. RESULTS Affinity chromatography of 1 g of E. fusca extract on lactose-Agarose column is shown in Fig.l. The lectin was eluted with 0.2 M lactose peak (B). Agglutination of human RBC was observed with protein from tubes number 30 to 35. Fig.2 shows PAGE at pH 8.4 of E. fusca lectin. Gel number 1 shows the crude extract stained with Coomassie brilliant blue. Gels number 2 and 3 show the purified lectin with only one protein band and the crude extract with several protein bands, both gels stained with Schiffreagent. Fig.3 shows SDS-PAGE of E. fusca and E. globocaliz lectins; both lectins show single protein bands corresponding to molecular weight of 28 000 for the monomelic form of the proteins (lanes 1 to 6). The multi-meric forms of the lectin are observed in lanes 7 to 12. The titer of the agglutination activity of E. fusca and E. globocaliz lectins is shown in Table 1, the inhibition of the agglutination activity in Table 2. The N-terminal amino acid sequence of the studied lectins compared with other Erythrina lectins is shown in Table 3. 0.75 . E E o €0 0.50. Û O 0 .25 . 0 . 00 10 20 30 40 TUBE NUMBER Fig. 1. Affinity chromatography of 1 g of E. fusca extract on lactose-Agarose column. Protein from peak A was eluted with 0.01M Tris/HCl + 0.02M CaC12, pH 7.2. Protein from peak B was obtained by elution with 0.2 M lactose + 0.15M NaCl. Agglutination of human RBC was observed with pro-tein from tubes 30 to 35. Similar pattern of elution was obtained for the lectin from E. globocaliz and E. costaricen-sis (data not shown). DISCUSSION It is inferred that the lectins from E. fusca and E. globocaliz are obtained as single band proteins, with a carbohydrate moiety. They are multimeric proteins and the molecular weight of the monomelic denatured protein was shown to be around 28 000. A similar staining behav-iour and molecular weight was also reported for the lectin of E. costaricensis ( Nanne-Echandi and Aragón-Ortiz 1991). The lectins did not differentiate between the human blood types studied. This activity was shown to be ARAGON & ORTIZ: Three Erythrina lectins 469 Fig. 2. Polyacrylamide gel electrophoresis of E. fiàsca lectin. Gel 1 shows the crude extract stained with Coomassie bril-liant blue. Gels 2 and 3 show the purified lectin and the crude extract both stained with Schiff reagent. Fig. 3. SDS-PAGE of the lectins from E. fusca and E. globocaliz.. (A) left lane : mol. wt standards (10 u,g each of the following proteins were applied: B. albumin, ovalbu-min, carbonic anhydrase, PMSF trypsinogen and soybean trypsin inhibitor). Lanes 1 to 3 EFusL: Lanes 4 to 6 EGL in both cases; 10, 15 and 20 u,g of lectin were applied respec-tively. (B) Left lane: mol. wt standards ( same as decribed above). Lanes 7 to 12 corresponds to EFusL and EGL in absence of SDS ; 10, 15 and 20 |ig of the lectins were applied respectively in each case. Table 2 Inhibitory action of carbohydrates over the hemagglutinat-ing activity of lectins from E. fusca and E. globocaliz toward human blood groups ABO, RhQ (D) positive and negative Blood group Inhibitor (0.1M) RhQ(D)+ Rh0(D)-Table 1 Titer of the agglutinating activity of the lectins from E. fusca and E.globocaliz, over the human blood groups ABO Rh0(D) positive and negative Blood group Lectin titer A B AB O 1:2 1:4 1:8 1:16 + + + + + + + + + A B AB O A B AB O Fucose + + + + + + + + Galactose Glucose + + + + + + + Mannose + + + + + + + + Fructose + + + + + + + + N-acetyl- + + + + + + + + mannosamine N-acetyl- - - - - - - - -galactosamine Xylose + + + + + + + + Inositol + + + + + + + + Mannitol + + + + + + + + Lactose Saccharose + + + + + + + + 470 REVISTA DE BIOLOGIA TROPICAL Table 3 Comparison of the amino terminal sequences of the studied lectins with several known N-terminal sequences from other legume lectins EFusL V E T I S F N F S E F E P G N N D L T L Q G A A L I EGL A E T MS F S F S Q F Q P G N N D L T L Q G V ECosL A E T M S F S F ECorL V E T I S F S F S E F E P G N D N L T L Q G D S * P ECL V E T I S F S F S E F E P G N ECafL V E T I S F S F S E F E P G N EFL A E T I S F S F S E F E P G EHL V E T I S F S F S E F E P G N ELysL V E T I S F S F S E EPL V E T I S F S F S K F E A G EZL V E T I S F S F S E F E P G N P N A A E T V S F N F N S F S E G N SBA A E T VS F S WN K F V P K E * Leucine or isoleucine. Data from Lis et al. (1985) and Adar et al. (1989). The following abbreviated names for the Erythrina lectins are used: EFusL» E. fusca; EGL, E. globocaliz; ECosL, E. costaricensis; ECorL, E. corallodendron; ECL, E. cristagalli; ECafL, E. caffra; EFL, E.flabelli-formis; EHL, E. humeana; ELysL, E. lysistemon; EPL, E. perrieri; EZLy E. zeyheri. For other legume lectins: PNA, peanut agglutinin; SBA, soybean agglutinin. inhibited by galactose, N-acetyl-galactosamine and lactose. A comparison of the N-terminal amino acid sequence of the lectins from E. fusca, E. globo-caliz and E. costaricensis with the N-terminal sequences of other 10 lectins (Lis et al 1985) as well as with the amino acid sequence of E. corallodendron (Adar et al 1989), a high per-centage of homology was observed, providing further evidence for the conservation of the lectin gene in legume plants. The lectins from E. fusca, E. globocaliz and from E. costaricensis (Nanne-Echandi and Aragón-Ortiz 1991), exhibi t many of the physicochemical properties already adscribed to other lectins characterized from the same family (Lis et al. 1985, Nanne-Echandi and Aragón-Ortiz 1991). All are glycoproteins with a neutral sugar content between 3-10%. After PAGE, they all give a positive reaction for car-bohydrates with the Schiff reagent (Fig.l). The proteins are mulümeric with a monomelic mol-ecular weight around 28 000. The agglutination of human RBC by E. fusca and E. globocaliz lectins as well as by E. costaricensis lect in (Nanne-Echandi and Aragón-Ortiz 1991), shows that these proteins behave similarly to ten other Erythrina lectins (Lis et al. 1985). They are unspecific in the agglutination of human RBC and the activity is inhibited by galactose, N-acetyl-galactosamine and lactose. These properties point out that the lectins bind to galactosyl receptors of the red cell membrane (Lis et al. 1985, Nanne-Echandi-Aragón Ortiz 1991). ACKNOWLEGEMENTS The authors are grateful to Jorge Gomez Laurito, School of Biology University of Costa Rica, for his collaboration in the taxonomical identification of the Erythrina trees. Federico Aragón Ortiz is a research fellow of the Costa Rican Nat ional Counci l for Science and Technology (CONICIT), contract 897274-75 J. RESUMEN Très lectinas obtenidas de extractos crudos, preparados de semillas de la Erythrina fusca, E. globocaliz y E. costaricensis fueron aisladas utilizando cromatografia de afinidad. Las lecti-nas son g l icopro te inas y en su forma monomérica presentan un peso molecular de 28 000. Las lectinas aglutinan eritrocitos humanos, independientemente del grupo sanguineo. La actividad aglutinante es inhibida por N-acetil-galactosamina, galactosa y lactosa. La secuen-cia N-terminal de cada lectina fue determinada mediante la degradación automatizada de Edman. Al compararlas con las secuencias de diez lectinas de leguminosas, se encontre una extensa homologia. REFERENCES Adar , R., M. Richardson, H. Lis & N. Sharon. 1989. The amino acid sequence of Erythrina corallodendron lectin and its homology with other legume lectins. FEBS Lett. 257: 81-85. ARAGON & ORTIZ: Three Erythrina lectins 471 Cumsky, M. & D. R. Zusman. 1979. Myxo bacterial hemagglutinin, a development spe-cific lectin of Myxococcus xanthus. Proc. Nad. Acad. Sci. U.S.A. 76: 5506-5509. Davis, B. J. 1964. Disc electrophoresis 2. Method and application to human serum proteins. Ann. N. Y. Acad. Sci. 121: 404-427. Edman, P. & Begg, G. 1967. A protein seque-nator. Eurp. J. Biochem. 1: 80-91. Flores, E. M. & D. I. Rivera. 1984. Clave para semillas y plântulas de las especies del gènero Erythrina en el Valle Central, Costa Rica. Rev. Biol. Trop. 32: 241-252. Laemmli, U. K. 1970. Cleavage of structural proteins during the assembly of the head of the bacteriophage T4. Nature 227: 680-685. Lis. H., F. J. Joubert & N. Sharon. 1985. Isolation and properties of N-acetylgalac-tosamine specific lec t ins from nine Erythrina species. Phytochemistry 24: 2803-2809. Nanne-Echandi, C. I. & Aragón-Ortiz, F. 1991. Aislamiento, purificación y caracterización de una lect ina de la semil la del poro , Erythrina costaricensis. Rev. Biol. Trop. 39: 15-21. 

A protein sequenator.

Aislamiento, purificación y caracterización de una lectina de la semilla del poro, Erythrina costaricensis.

Clave para semillas y plântulas de las especies del gènero Erythrina en el Valle Central,

Cleavage of structural proteins during the assembly of the head of the bacteriophage T4.

Disc electrophoresis 2. Method and application to human serum proteins.

Isolation and properties of N-acetylgalactosamine specific lectins from nine Erythrina species.

The amino acid sequence of Erythrina corallodendron lectin and its homology with other legume lectins.

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Properties and N-Terminal amino acid sequences of three Erythrina lectins from Costa Rica (Leguminosae)

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