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Biomedical subjects

S Gatt

Publications and source records attributed to S Gatt.

At least 145 records · Page 8Linked to original sources
PubMed1977

Rate equations and simulation curves for enzymatic reactions which utilize lipids as substrates. I. Interaction of enzymes with the monomers and micelles of soluble, amphiphilic lipids.

Theoretical aspects of the kinetics of interaction of enzymes with lipid substrates are presented. Rate equations were written and used to simulate v versus S curves for interaction of enzymes with "monomers" (i.e. a molecular solution) or micelles (aggregated form) of the "soluble", amphiphilic lipids. The rate equations were written assuming separate kinetic parameters for the interaction of the enzyme with these two forms. Although the rate equations are based on the kinetic theory of Michaelis and Menten, most of the simulated v vs. S curves were not hyperbolic. A procedure is suggested for determining the kinetic parameters with the aid of a graphic method.

Colloids↗
PubMed1977

Rate equations and simulation curves for enzymatic reactions which utilize lipids as substrates. II. Effect of adsorption of the substrate or enzyme on the steady-state kinetics.

Theoretical aspects of the kinetics of interaction of enzymes with lipid substrates are presented. Rate equations were written and used to simulate v versus S curves for the following cases: (a) The substrate is adsorbed onto non-catalytic sites of the enzyme or to other proteins accompanying the enzyme. (b) The enzyme is adsorbed, via non-catalytic sites to aggregated forms of the substrate. (c) The substrate is adsorbed onto an externally added protein such as albumin. Although all rate equations are based on the Michaelis-Menten kinetic theory, most of the simulated v vs. S curves were not hyperbolic and some of the v vs. E curves not linear.

Adsorption↗
PubMed1976

Effect of Triton X-100 on the hydrolysis of sphingomyelin by sphingomyelinase of rat brain.

Mixed dispersions of the nonionic detergent Triton X-100 and sphingomyelin were used as substrate for sphingomyelinase of rat brain. The dependence of the rate of hydrolysis on the concentration of sphingomyelin was measured in two ways: at a fixed concentration of Triton X-100 or at varying concentrations of this detergent, while maintaining a fixed molar ratio of Triton X-100 to sphingomyelin. In either case, the upsilon vs. S curves deviated from the hyperbolic shape predicted by the Michaelis-Menten kinetic theory. These deviations are discussed and interpreted on the basis of the physicochemical properties of the mixed dispersions of detergent and lipid studied in previous papers.

Animals↗
PubMed1976

Hydrolysis of neutral glycerides by lipases of rat brain microsomes.

The hydrolysis of monoacylglycerol and diacylglycerol by rat brain microsomes was followed by measuring the release of glycerol and monooleylglycerol from dispersions of water insoluble glyceryl esters of oleic acid. The microsomes showed three lipolytic activities. One activity, optimal at pH 4.8, catalyzed the hydrolysis of diacylglycerol but not monoacylglycerol. Two other lipolytic activities, optimal at pH 8.0-8.6, catalyzed the hydrolysis of both diacylglycerol and monoacylglycerol. The pH 8.0-8.6 activities were sensitive to heat and SH-reagents. Detergents were inhibitory in all cases. Extraction of the microsomes with KCl, KSCN, urea or Triton X-100 did not change the ratio of diacylglycerol hydrolysis at pH 4.8 and 8.0. The results of subcellular fractionation studies showed that there was no significant enrichment of the acid lipase in any fraction.

Animals↗