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We investigated the effect of proteases, widely used for neuron isolation in electrophysiological studies, on the amplitude and kinetic characteristics of persistent sodium current (I(NaP)) in hippocampal CA1 pyramidal neurons. Properties of I(NaP) were studied on neurons isolated by mechanical treatment (control group) and by mechanical and enzymatic treatment using pronase E (from Streptomyces griseus) or protease type XXIII (from Aspergillus oryzae). We show that in neurons isolated with pronase E kinetic of activation and density of I(NaP) was unaltered. Enzymatic treatment with protease type XXIII did not alter I(NaP) activation but result in significant decrease in I(NaP) density. Our data indicates that enzymatic treatment using pronase E for neuron isolation is preferable for investigation of I(NaP).

Microbial keratinolytic enzymes hydrolyze such a hard dissoluble protein substrate as keratin. Data conserning ability to degrade keratin by various groups of microorganisms and their potential biological role are discussed in the paper. The physical and chemical properties of enzyme preparations of keratinases and methods of their separation and purification have been examined. The available and possible ways of these enzymes application in industry and medicine have been discussed.

Antihypertensive peptides were obtained after the proteolysis of beta-casein by starter cells Lactococcus lactis ssp. lactis and lactococci with pepsin or fromase. The peptides have shown the effect as inhibitors of angiotensin-converting enzyme. The strongest action the peptide obtained after the proteolysis of beta-casein by synergic action of lactococci with pepsin has shown. It demonstrates a capability of formation of such peptides directly in milk products during their making and maturation under the action of proteolytic system of lactic acid bacteria and milk clothing proteases.

The immunological properties of water-soluble acid neurospecific antigens A and D of the bull brain were studied as affected by heating and proteolytical enzymes (trypsin, mixture of trypsin and alpha-chymotrypsin, protease from Streptomyces griseus). The immunological activity of antigen A is not changed essentially after its heating for 20 min at a temperature of 70-80 and 24-hour proteolysis with trypsin. Heating at 90-100 C as well as hydrolysis with protease from Streptomyces griseus and mixture of trypsin with alpha-chymotrypsin for the same time decrease the immunological activity of antigen A. The immunological activity of antigen A lowers after heating for 20 minutes at a temperature of 60 C and the action of all the studied proteolytical enzymes for 24 hours. The data obtained evidence for protein nature of antigens A and D.