7種海藻中における第4級アンモニウム塩基の分布

最近,海洋生化学資源の開発が重要視され,海産物由来のいくつかの有効物質が単離・同定されて,その生化学的および薬理学的役割が検討されてきている。その中で,海藻中にも2,3の有効物質が明らかにされてはいるものの,その数は少ない。本研究では,海藻中の有効物質が含窒素化合物に多いことから,海藻中の第4級アンモニウム塩基を7種の紅藻および緑藻を用いて検索した。 各海藻の70%エタノール抽出液中の第4級アンモニウム塩基をイオン交換カラムクロマトグラフィーを用いて単離・精製し,そのTLC上のRf値,IRスペクトルおよび融点を測定して,購入および合成した既知の第4級アンモニウム塩基のそれらと比較することにより同定した。その結果, laminine, candicine, stachydrine, glycine betaine, betonicine, β-homobetaineおよびγ-boutyrobetaineと2種の未同定塩基を検出した。candicineが海藻中から単離・同定されたのは,今回が最初と思われる。これら塩基の海藻種間における分布に関しては,特に特異性は認められなかった。Seven species of marine red and green algae were examined for quaternary ammonium bases. Nine bases were purified and isolated by ion exchange column chromatography from the ethanolic extracts of the algae. The isolated bases were identified by measuring their Rf values in thin layer chromatography, infrared spectra and melting points in comparison with specimen of thirteen kinds of authentic quaternary ammonium bases which were prepared by commercial means or syntheses. As the results, seven bases; laminine, candicine, stachydrine, glycine betaine, betonicine, β-homobetaine and γ-butyrobetaine, and two unidentified bases were detected. It was first demonstrated that candicine is present in marine algae. There is no essential difference in the distribution of the bases among the species of marine algae examined here

数種サンゴモ科海藻エキスのアミノ酸組成とペプチッド

6種17検体のサンゴモ科海藻エキスの加水分解前後のアミノ酸組成を調べた。その結果、加水分解前にほ一般にalanine、glycineおよびtaurineの含量が比較的高かった。またL-baikiainをサンゴモ(Corallina officinalis)より分離同定し、これがサンゴモ科の海藻に広く分布することを認めた。加水分解後には全ての試料においてaspartic acidとglutamic acidを中心として著量のアミノ酸の増加が認められ、これら海藻エキス中にかなり多量のペプチッドの存在することが推定された。サンゴモのエキスのペプチッド成分を検索した結果、酸性および強酸性区分中にaspartic acidとglutamic acidを主要な構成成分とするかなり多数のペプチッドの存在が認められた。これらのうちα-aspartylisoleucineとα-aspartylleucineの存在を確認した。Amino acid patterns before and after hydrolysis in several species of Corallinaceae algal extracts were examined by means of amino acid analyzers. Before hydrolysis, alanine, glycine and taurine were predominant in general. Occurrence of L-baikiain was also confirmed and its wide distribution in Corallinaceae algae was observed. These calcareous algal extracts showed a remarkable increase of amino acids after hydrolysis, especially aspartic acid and glutamic acid, suggesting the presence of a fairly large amount of peptides. In the examination of peptidyl compounds in C. officinalis, some acidic peptides mainly consisting of aspartic acid and glutamic acid were found to exist. Among them, occurrence of α-aspartylisoleucine and α-aspartylleucine was confirmed

Primary Structure and Carbohydrate Binding Specificity of a Potent Anti-HIV Lectin Isolated from the Filamentous Cyanobacterium Oscillatoria agardhii

The primary structure of a lectin,designated OAA, isolated from thefreshwater cyanobacterium, Oscillatoriaagardhii NIES-204, was determined by thecombination of Edman degradation andESI-mass spectrometry. OAA is apolypeptide (MW 13,925) consisting of twotandem repeats. Interestingly, each repeatsequence of OAA showed a high degree ofsimilarity to those of a myxobacterium,Myxococcus xanthus hemagglutinin(MBHA), and a marine red alga Eucheumaserra lectin (ESA-2). A systematic bindingassay with pyridylaminated oligosaccharidesrevealed that OAA exclusively binds to highmannose (HM) type N-glycans, but not toother N-glycans, including complex types,hybrid types and the pentasaccharide core,or oligosaccharides from glycolipids. OAAdid not interact with any of free mono-andoligomannoses that are constituents of thebranched oligomannosides. These resultssuggest that the core disaccharide, GlcNAc-GlcNAc, is also essential for binding to OAA.The binding activity of OAA to HMtype N-glycanswas dramatically decreased whenα1-2 Man was attached to α1-3 Manbranched from the α1-6 Man of thepentasaccharide core. This specificity ofOAA for HM type oligosaccharides isdistinct from other HM-binding lectins.Kinetic analysis with an HMheptasaccharide revealed that OAApossesses two carbohydrate-binding sitesper molecule, with an association constant of2.41×10^8M^-1. Furthermore, OAA potentlyinhibits HIV replication in MT-4 cells(EC50=44.5 nM). Thus, we have found anovel lectin family sharing similar structureand carbohydrate binding specificity amongbacteria, cyanobacteria, and marine algae

Purification, Characterization, and cDNA Cloning of a Novel Lectin from the Green Alga, Codium barbatum

A novel lectin (CBA) was isolated from the green alga, Codium barbatum, by conventional chromato- graphic methods. The hemagglutination-inhibition pro- file with sugars and glycoproteins indicated that CBA had preferential affinity for complex type N-glycans but not for monosaccharides, unlike the other known Codium lectins specific for N-acetylgalactosamine. CBA consisted of an SS-linked homodimer of a 9257- Da polypeptide containing seven cysteine residues, all of which were involved in disulfide linkages. The cDNA of the CBA subunit coded a polypeptide (105 amino acids) including the signal peptide of 17 residues. The calcu- lated molecular mass from the deduced sequence was 9705Da, implying that the four C-terminal amino acids of the CBA proprotein subunit were post-translationally truncated to afford the mature subunit (84 amino acids). No significantly similar sequences were found during an in silico search, indicating CBA to be a novel protein. CBA is the first Codium lectin whose primary structure has been elucidated