l88 BIOCHIMICA ET BIOPHYSICA ACTA VOL. 12 (iQoj) 



THE ENZYMIC OXIDATION OF d- AND /-/9-HYDROXYBUTYRATE* 



by 



ALBERT L. LEHNINGER** and GUY D. GREVILLE 



Department of Physiological Chemistry, Johns Hopkins School of Medicine, Baltimore, Md., (U.S.A.) 

 and the Department of Biochemistry, The University, Cambridge {England) 



Ever since the isolation of ^-^-hydroxybutyric acid*** from the urine of diabetics 

 was first reported by Magnus-Levy^, this substance has been regarded as an intermediate 

 in the metabohsm of fatty acids although its exact role is still obscure. The only known 

 enzyme attacking it, the /-specific DPN-linked ^-hydroxy butyric dehydrogenase^, con- 

 verts it into acetoacetate, which is now known to be oxidized to completion in various 

 tissues via the tricarboxylic acid cycle. 



Although the /-isomer has been commonly regarded as the "naturally occurring" 

 form, some evidence exists that the ^/-isomer undergoes biological utilization. In igo2 

 McKenzie demonstrated that the J-isomer is metabolized by the intact dog and 

 apparently at a greater rate than the /-isomer, a finding which was confirmed by Dakin''. 

 Furthermore, Friedmann demonstrated in 1931 that fermenting yeast reduces aceto- 

 acetate to dextrorotatory /3-hydroxybutyrate^. More recently it has been found that 

 both isomers of the racemic compound undergo oxidation in suspensions of particulate 

 elements (mitochondria) from liver and kidney^' ^^. We have made similar observations, 

 some of which indicated that the two isomers have soinewhat different pathways of 

 oxidation in liver preparations. In this communication we wish to present data obtained 

 employing the pure stereoisomers of ^-hydroxybutyric acid which delineate the different 

 enzymic pathways taken by the two forms. From these findings it appears probable 

 that the ^f-isomer is also of "natural occurrence" and that it plays a role in ketone body 

 and fatty acid metabolism. 



experimental details 



Resolution of dl-(i-hydroxybutyric acid. ^/-/5-hydroxybutyric acid, prepared from the sodium 

 salt (British Drug Houses), was converted into the calcium-zinc double salt^^ which was recrystallized. 

 Resolution of the purified acid regenerated from the double salt was based on the method of Clarke^^, 



* This work was supported in part by grants from the Nutrition Foundation, Inc., and from the 

 National Institutes of Health, U.S. Public Health Service. 



** A.L.L.was a Fellow of the John Simon Guggenheim Foundation and a Research Scholar under 

 the Fulbright Act in the Department of Biochemistry, University of Cambridge, when this investiga- 

 tion was initiated and he wishes to express his gratitude to Prof. F. G. Young, F.R.S., for the 

 hospitality of his laboratory. 



*** Throughout this paper the designation /-/3-hydroxybutyric acid (/-BOH) refers to levorotatory 

 ^-hydroxybutyric acid and ^-/?-hydroxybutyric (li-BOH) refers to the dextrorotatory form in accord- 

 ance with long usage in the case of this particular compound in the biochemical literature. However, 

 it should be pointed out that the configurational relationships of the /^-hydroxybutyric acids to the 

 lactic acids have been definitely established^- 2-^. Thus levorotatory BOH is of the D-series and should 

 be designated as d( — )/?-hydroxybutyric acid and the dextrorotatory form as L(H-)/3-hydroxybutyric 

 acid. 



References p. 202. 



