title: 3-Hydroxyisobutyrate dehydrogenase, an impurity in commercial 3-hydroxybutyrate dehydrogenase.
abstract: The enzymic determination of D-3-hydroxybutyrate and acetoacetate normally involves the use of 3-hydroxybutyrate dehydrogenase (HBDH, EC 1.1.1.30) of bacterial origin. We show that HBDH from Rhodopseudomonas spheroides (BCL, grade II) contains a 3-hydroxyisobutyrate dehydrogenase (HIBDH) activity: activity with 3-hydroxyisobutyrate as substrate was greater than 10% of that with 3-hydroxybutyrate. However, HBDH could be prepared essentially free of HIBDH activity by incubation at 37 degrees C in the presence of 1 mM-CaCl2, to produce an enzyme preparation that may be used for the specific determination of 3-hydroxybutyrate. Use of the purified enzyme preparations indicated that a major product of valine metabolism in hemidiaphragms from 40 h-starved rats was 3-hydroxyisobutyrate rather than 3-hydroxybutyrate.
mesh_terms: D000818:Animals; D002850:Chromatography, Gel; D004340:Drug Contamination; D006358:Hot Temperature; D006884:Hydroxybutyrate Dehydrogenase / Q000302:isolation & purification* / Q000378:metabolism; D066298:In Vitro Techniques; D007930:Leucine / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012242:Rhodobacter sphaeroides / Q000201:enzymology; D013217:Starvation; D014633:Valine / Q000378:metabolism
chemical_list: D006884:Hydroxybutyrate Dehydrogenase; D007930:Leucine; D014633:Valine