Effect of Insulin, Epinephrine, Hydrocortisone and ACTH on the Catheptic Activity of Rat Spleen

In our experiments under in vivo conditions we followed ·the response of spleen on injected insulin, epinephrine, hydrocortisone and ACTH. Insulin caused a decrease in spleen weight, a decrease of protein nitrogen and an increase of catheptic activity 30 min. after application. Afterwards catheptic activity was significantly above control value in 60 min. (expressed in E. U./g. tissue) although· decreasing tendency was observed. 30 and 60 min. after epinephrine application spleen weight and protein nitrogen were increased whereas catheptic activity remained under the control value (expressed in E. U./mg.N). After 3 hrs the spleen weight was reduced (reduced protein nitrogen) whereas catheptic activity was significantly increased, specially if expressed in E. U./g. tissue. Hydrocortisone caused a decrease in spleen weight and protein nitrogen. Catheptic activity was significantly above control value 30 min. and 3 hrs after application, if expressed in enzyme unit per gram tissue. Two hours after ACTH administration protein nitrogen was increased, whereas catheptic activity was under the control value (expressed in E. U.jmg. N)

A Quantitative Chromatographic Method for the Determination of Leucine Aminopeptidase Activity

A micro method for the determination of leucine aminopeptidase activity was developed. Leucinamide was us ed as substrate. The liberated leucin e was quantitative ly determined using paper chromatography a nd reflectanc e-densitometrical scanning of the spots. From the spot area of leucine the enzyme activity was evaluated. This method is useful for the determination of leucine aminopeptidase activity in supernatants obtained after centrifugation of homogenized organs

Acid Proteinases from Calf Lymph Nodes

Acid proteinases were isolated from calf lymph nodes using acid extraction, ammonium sulphate and acetone precipitation, followed by ion exchange chromatography on CM-cellulose and _ gel chromatography on Sephadex G-100. Cathepsin D (E. C. 3.4.23.5) is present in lymph nodes. It has the molecular weight of 39 000 as determined by gel filtration on Sephadex G-100. Cathepsins Bl and B2 (E. C. 3.4.22.1) were also isolated. Molecular weights of 22 000 and 51 000 were determined for cathepsins Bl and B2, respectively. Calf lymph nodes contain also another proteinase which degrades haemoglobin at an optimum at pH = 3.0. This proteinase has a molecular weight of 14 000 as was determined by gel filtration. Its activity is not inhibited with 0,25 ~tM pepstatin which inhibits 903/o of the cathepsin D activity

Purification and some Properties of Proteinases from Calf Thymus

Calf thymus was used for the investigation of intracellular proteinases. The tissue was homogenized, centrifuged at a low speed and applied on DEAE-cellulose. Active fractions were collected and their proteolytic activity toward different protein substrates was tested. It was found that several proteinases are present in thymus; cathepsin D being the most abundant acid proteinase. The activitiy at neutral pH was ascribed to fibrinogen degrading proteinases

A Quantitative Chromatographic Method for the Determination of Leucine Aminopeptidase Activity

A micro method for the determination of leucine aminopeptidase activity was developed. Leucinamide was us ed as substrate. The liberated leucin e was quantitative ly determined using paper chromatography a nd reflectanc e-densitometrical scanning of the spots. From the spot area of leucine the enzyme activity was evaluated. This method is useful for the determination of leucine aminopeptidase activity in supernatants obtained after centrifugation of homogenized organs