SEPARATION AND RELATIVE QUANTITATION OF MOUSE PLASMA ESTERASES WITH DISC ELECTROPHORESIS

A technique for the qualitative and quantitative study of mouse plasma esterases using disc electrophoresis in acrylamide gel is described. This technique has been employed to study substrate specificity and quantitative relationships among various mouse strain and sex dependent esterases. Properties of acrylamide gels are discussed relative to their effect on the quantitative estimation of plasma esterases.

The study of urinary protein excretion in male rats as compared with human proteinuria

Male rats are widely used for comparative investigations in renal physiology and pathology. However, they demonstrate a striking physiological proteinuria which must be considered if protein excretion is one parameter in the description of a model. Electrophoretic differentiation of urinary proteins shows that the major portion of male urinary protein consists of low molecular weight proteins which are strain-, sex- and age-dependent. The excretion of these proteins depends mainly on sex hormones and only to a lesser degree on kidney function. The excretion of albumin is a sensitive indicator to detect glomerular permeability changes, mainly because the tubular transport maximum is restricted and because the concentration difference between glomerular ultrafiltrate and plasma is very large, so that a small increase in permeability may cause a greatly elevated albumin excretion. Therefore, selective determination of albumin, e.g., by electrophoretic separation, is indispensable to estimate the renal permeability. Complicating the evaluation of experimental results, spontaneous kidney disease (progressive glomerulonephritis or glomerulosclerosis) develops in aging rats. Therefore, long-term studies in rats should be avoided because this spontaneous kidney disease with concomitant changes in protein excretion might interfere with experimental results.

Detection of thrombin-induced fibrinogen derivatives in thrombotic states

Affinity chromatographic studies using insolubilized fibrinogen (fibrinogen-agarose) revealed that fibrin monomer present in plasma is selectively adsorbed to fibrinogen-agarose and may be quantitatively estimated following desorption. Analysis of plasma samples from patients with myocardial infarction, cirrhosis of the liver malignant diseases and DIC confirmed the presence of considerable amounts of fibrin monomer revealing concentrations between 3 and 15 mg/100 m1 plasma as compared to normal plasma (1.96 +/- 0.37 mg/100 m1, = 27). The method is suitable for the assessment of hypercoagulable states. Standard conditions for the procedure were evaluated using 3H-labelled fibrinogen and fibrin monomer.

Polymorphic serum prealbumin (Pa) of pig, identified as and alpha1-protease inhibitor

Pig serum proteins were analysed by horizontal polyacrylamide gel electrophoresis, with a discontinuous buffer system (pH 9.0). A 12% acrylamide concentration in the separation gel was used. Each of the two paralbumin (Pa) alleles gave rise to two closely migrating fractions. The polymorphic Pa was identified as an alpha1-protease inhibitor as the Pa fractions inhibited the esterolytic activity of both bovine trypsin and chymotrypsin. Therefore, it has been proposed that the locus symbol for this prealbumin be changed to Pi-1. The protease inhibitory spectra and electrophoretic mobility of the Pa (Pi-1) fractions suggested that this protein was probably the same as the pig serum alpha1-protease inhibitor described in some earlier studies and that it corresponds to human serum alpha 1-protease inhibitor (Pi).

Deamidated active intermediates in the irreversible acid denaturation of ribonuclease-A

A study has been made on the changes in the enzymatic activity of Ribonuclease-A**-(RNase-A) exposed to highly acidic (pH less than 1) acqueous environment. Irreversible alterations of activity were observed when the protein was exposed to an acidic medium for a long period (20 to 60 h). Even prior to these changes in activity RNase-A was found to form intermediates which had very nearly the same activity as the native protein. The primary process in the acid denaturation of RNase-A was observed to be deamidation of the protein leading to the formation of active chromotographically distinct derivatives. The initial product of deamidation, a monodeamidated derivative, has been isolated by chromatography on Amberlite XE-64. This initial deamidation reaction proceeded with very high specificity. The subsequent deamidation reaction is comparatively slower, so that nearly 50% of the native protein could be converted to this derivative before any subsequent deamidation took place. This monodeamidated derivative has been designated RNase-Aa1. The conversion of RNase-A to RNase-Aa1 was not accompanied by any changes in the primary structure other than the observed deamidation. Apart from the differences in chromatographic and electrophoretic mobilities, RNase-Aa1 was found to have very nearly the same activity and physicochemical properties as the native enzyme. Significance of this specific and faster deamidation of RNase-A in this denaturing medium as well as the biological significance of such deamidation reactions of proteins are discussed.

On the reactivity of carboxyl groups of ribonuclease-A in anhydrous methanol

The esterification of Ribonuclease-A in methanol/0.1 M hydrochloric acid has been studied by measuring the decrease in the number of titratable groups of the protein and estimating the amount of methanol incorporated. Esterification of nearly five of the 11 free carboxyl groups of the protein resulted in almost complete inactivation of the enzyme. The initial products of esterification have been chromatographed on Amberlite columns, and five partially active methyl ester derivatives of Ribonuclease-A have been isolated. The dimethyl ester, the initial product of esterification with reduced catalytic activity, has the carboxyl groups of Glu-49 and Asp-53 modified. Even in the non-aqueous solvent, as in the native structure of the protein in aqueous solution, these carboxyl groups are the fast reacting ones. Subsquently, the esterification reaction appears to proceed preferentially at the C-terminal region of the molecule. Comparison of the reactivities of carboxyl groups of Ribonuclease-A in acidic methanol to that known in aqueous solutions (with carbodiimides) suggests that the structure of Ribonuclease-A in the non-aqueous solvent resembles, at least in part, the structure in aqueous environment.

Separation of the two double-chain bovine intermediates of the proinsulin-insulin conversion I. Chemical, immunochemical, circular dichroism, and biological characterization

The intermediates of the proinsulin-insulin conversion were separated by cation exchange. The circular dichroism spectra of the intermediates showed less alpha-helix than insulin and proinsulin. It is suggested that the C-peptide interacts with the section of alpha-helix contained between residues 2 and 8 in the A-chain of the insulin moieties and unwinds the alpha-helix. The in vivo activities of the intermediates were found to be in the order of 50% relative to insulin. In the fat cell assay, the A-chain-substituted form is weaker (9%) than the B-chain-substituted form (19%). The C-peptide segments of the two forms reacted with C-peptide-specific antibodies as fully as the free C-peptide, on a molar basis. In contrast, the insulin segments were hindered from reacting with insulin-specific antibodies as fully as the insulin.

Purification of Human Leukocyte Elastase and Cathepsin G by Chromatography on Immobilized Elastin

Human leukocyte elastase and cathepsin G were isolated from purulent sputum by a simple procedure involving chromatography on elastin-agarose. Salt extracts of sputum were prepared, treated with DNase, and the precipitate which formed extracted and applied to a column of soluble elastin-Sepharose 4B. Contaminating protein was eluted with 50 mM Tris, 50 mM NaCl, pH 8.0 and then two column volumes of 50 mM acetate, 1.0 M NaCl, pH 5.0. The tightly bound elastase and cathepsin G together with a trypsin-like serine protease could finally be eluted with 50 mM acetate, 1.0 M NaCl, 20% DMSO, pH 5.0. Resolution of the proteases was accomplished by cation-exchange chromatography. Disc gel electrophoresis established the purity of elastase and cathepsin G and confirmed the existence of several isozymes for each.

[Population analysis of electrophoretic variation in blood serum albumins of European (Acipencer ruthensis L.) and Siberian (A. ruthensis marsiglii Brandt) sterlet]

We studied blood serum albumins in European (Acipencer ruthensis L.) and Siberian (A. ruthensis marsiglii Brandt) sterlet using disk electrophoresis in polyacrylamide gel. The albumins were shown to be controlled by three codominant alleles of a single locus (ALB*a, b, c). In European sterlet, all three theoretically possible genotypes were described, one of which (ALB*c/c) occurred extremely rarely (one individual). Siberian sterlet was found to be monomorphic for albumins: all fish examined had the ALB*a/a genotype. There was no correlation between albumin patterns and fish fatness. In a number of samples from the Volga River basin, spatial and temporal differentiation was found and analyzed. The results suggest that construction of hydroelectric plants may provoke massive and prolonged starlet migrations.

Enzymatic studies of riboflavin oversynthesis in Eremothecium ashbyii

Mechanisms of riboflavin oversynthesis in a high flavinogenic mold, Eremothecium ashbyii, were examined in relation to growth, riboflavin formation and related synthases, and medium pH with increasing culture periods. Growth reached maximum at 1 d and then decreased, riboflavin formation proceeded rapidly up to 5 d and approached almost a plateau region. The medium pH reached minimum at 1 d and thereafter fairly rapidly increased until 3 d, then gradually increased to 7 d after cultivation. The crude enzyme solution from the mycelia at specified culture periods was run through a column of Sephadex G-200, indicating two riboflavin synthase activities on the chromatogram. The fluctuation of the growth and the specific activities of the two enzymes were examined with increasing culture periods, which showed that the heavy enzyme may be a constitutive one and that the light enzyme may be concerned with the oversynthesis of riboflavin in E. ashbyii. The heavy enzyme was then purified by 49-fold after dialysis of the ammonium sulfate precipitate by a series of column chromatographies with Sephadex G-200, hydroxyapatite, DEAE-Sepharose A-50 and DEAE-cellulose. The purified enzyme which was treated with weak alkaline solution was broken into the light enzyme, showing two bands on an acrylamide disc gel electrophoresis. The relation of the heavy and the light enzymes to the oversynthesis of riboflavin in E. ashbyii was discussed.