Protein hydrophobicity and stability support the thermodynamic theory of protein degradation.
Rat liver enzymes were used to study the relationship between their in vivo half-lives and their apparent hydrophobicity or their resistance to inactivation by mechanical shaking. The apparent hydrophobicity of these enzymes, measured as the percent of the protein recovered from an octyl-Sepharose column, is correlated with their known half-lives (r = 0.75, P less than 0.01). The presence of specific ligands which are known to increase compactness by impeding unfolding of proteins decreased the apparent hydrophobicity of fructose-1,6-bisphosphatase, glucose-6-phosphate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, and pyruvate kinase. Resistance of enzymes to inactivation by mechanical shaking correlated well with their in vivo half-lives (r = 0.90, P less than 0.01). When the shaking experiments were done in the presence of substrates, fructose-1,6-bisphosphatase, glucose-6-phosphate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase were protected from inactivation.
D000818:Animals; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D006597:Fructose-Bisphosphatase / Q000037:antagonists & inhibitors*; D005954:Glucosephosphate Dehydrogenase / Q000037:antagonists & inhibitors*; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000037:antagonists & inhibitors*; D006207:Half-Life; D008099:Liver / Q000201:enzymology*; D008297:Male; D009243:NAD / Q000494:pharmacology; D009249:NADP / Q000494:pharmacology; D011487:Protein Conformation; D011770:Pyruvate Kinase / Q000037:antagonists & inhibitors*; D051381:Rats; D011919:Rats, Inbred Strains; D013816:Thermodynamics
D009243:NAD; D009249:NADP; D005954:Glucosephosphate Dehydrogenase; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D011770:Pyruvate Kinase; D006597:Fructose-Bisphosphatase