Native and acid-denatured L-lactate dehydrogenase are different in the lysosomal proteinases involving in their overall degradation.
When native and (LDH) acid-denatured lactate dehydrogenase were incubated with total lysosomal enzymes in vitro, amino acids from their degradation were produced at various acidic pH. The pH profile in the overall degradation of native LDH was markedly different from that of acid-denatured LDH. Disappearance of the 35-kDa subunit of native LDH was markedly suppressed by a low level of cystatin alpha as well as by a general cysteine proteinase inhibitor, N-(L3-trans-carboxyoxirane-2-carbonyl)-L-leucine-3-methylbutylamid e (E-64-c). On the other hand, the degradation of acid-denatured LDH was only slightly suppressed by these inhibitors. It was concluded that at least a part of the proteinases involved in the overall degradation of native LDH is different from the proteinases involved in the degradation of acid-denatured form and a role of a cystatin alpha-sensitive cysteine proteinase is critical in the lysosomal degradation of native LDH, but not in that of acid-denatured form.
Ohshita
T
T
School of Food and Nutrition, Shokei Junior College, Kumamoto, Japan.
D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D007770:L-Lactate Dehydrogenase / Q000737:chemistry* / Q000378:metabolism; D008247:Lysosomes / Q000201:enzymology*; D011487:Protein Conformation; D011489:Protein Denaturation
D007770:L-Lactate Dehydrogenase; D003546:Cysteine Endopeptidases