Some effects of polyvinyl alcohol and polyvinyl pyrrolidone on the activity of lactate dehydrogenase and its isoenzymes

Summary The activity of Sigma type II LDH (containing all LDH isoenzymes), type VII (LDH 1) and type V (LDH 5) has been evaluated in 0.1 M phosphate buffer and 0.4 M tris-HCl buffer, both at pH 7.4, before and after addition of PVP and PVA. A slight reduction of reaction velocity occurred when PVP and PVA were added, probably because of the increased viscosity of the medium. More specifically, PVA seemed to reduce the LDH 1 activity in phosphate buffer, but it seemed to counteract, together with PVP, conformational changes due to tris-HCl buffer of high molarity. None of these effects were found to influence the results of section histochemistry, but it could be shown that PVA was able to reduce urea inhibition of LDH 5 in tris-HCl buffer.The following Abbreviations are used in the Article PVA Polyvinyl alcohol - PVP Polyvinyl pyrrolidone - tris tris (hydroxymethyl)-aminomethan - LDH Lactate dehydrogenase - -NADH -Nicotinamide Adenine Dinucleotide, reduced form - PMS Phenazine methosulfate - BSA Bovine serum albumin