hydroxybutyrate and DPN+ and the amounts of DPNH formed were measured. Phosphate buffer was used at pH 7 and tris buffer at the fnore alkaline pH values. Controls containing all reagents except P-hydroxybutyrate or acetoacetate showed no significant changes in extinction. The results of 14 individual measurements showed good agreement (Table 1). The mean value for K was 1-42 + 0 19 (S.D.) X 10-...

Splanchnic arterio-hepatic venous differences for a variety of substrates associated with carbohydrate and lipid metabolism were determined simultaneously with hepatic blood flow in five patients after 3 days of starvation. Despite the relative predominance of circulating beta-hydroxybutyrate, the splanchnic productions of both beta-hydroxybutyrate and acetoacetate were approximately equal, tot...

1. The role of enhanced aerobic glycolysis in the transformation of rat thymocytes by concanavalin A has been investigated. Concanavalin A addition doubled [U-(14)C]glucose uptake by rat thymocytes over 3h and caused an equivalent increased incorporation into protein, lipids and RNA. A disproportionately large percentage of the extra glucose taken up was converted into lactate, but concanavalin...

Until recently the views prevalent in the literature with respect to ketone formation in the normal and diabetic organism were as follows: The long fatty acid carbon chains are split by successive /3 oxidation, 2 carbons at a time, with the formation of intermediate shorter fatty acids and acetic acid (Knoop hypothesis). Normally this process continues to completion, but in the absence of suffi...

1. In liver, rumen epithelium and kidney cortex of the sheep, a dehydrogenase active against dl-3-hydroxybutyrate occurred in both the cytosol and particulate fractions of the tissues. In brain, heart, skeletal and smooth muscles, the enzyme occurred only in the particulate fraction. 2. Enzyme activity in the cytoplasmic fraction of liver and rumen epithelium was similar with either d(-)-3-hydr...

H. A. KREBS, P. K. JENSEN AND L. V. EGGLESTON I958 3. Adenosine 5'-phosphate, L-aspartate, L-asparagine, fumarate and glycerol each stimulated 'factor' activity but had no effect on the enzymic hydrolysis ofcarbamyl phosphate. This stimulation generally increased with time. 4. Some characteristics ofthe bacterial hydrolysis of carbamyl phosphate are described. 5. The results indicate that the b...

Factors that may initiate the metabolic transition for butanol production were investigated in batch cultures of Clostridium beijerinckii (synonym, Clostridium butylicum) VPI 13436. Cultures maintained at pH 6.8 produced nearly as much butanol as those incubated without pH control, indicating that neither a change in the culture pH nor acid conditions per se are always required to initiate solv...

Previously, we have shown the preferential incorporation of label from [3-‘%]acetoacetate, D-( -)-3-hydroxy[3-%]butyrate, and [2-‘4C]glucose into sterols and fatty acids in brain in Id-day-old rats. In these experiments, we assumed that the labeled metabolites would be used from the blood in the form which was injected. However, during metabolic processes, a labeled metabolite which is present ...

In Paper V of this series (1) it was found that the citrate which accumulates during the oxidation of W-tagged acetoacetate by rat kidney in the presence of oxalacetate had a high content of isotopic carbon, thus confirming the participation of tricarboxylic acids in the oxidation of fatty acid intermediates. The present study represents a continuation of the investigation of this reaction with...

Soluble cell-free extracts of actinomycete S4 grown on media containing mevalonate catalyze acetoacetate formation from mevalonate, mevaldate, and beta-hydroxy-beta-methylglutaryl-coenzyme A (CoA). Conversion of mevalonate to acetoacetate involves formation of free beta-hydroxy-beta-methylglutaryl-CoA, but not free mevaldate. The reaction favors mevalonate oxidation, and nicotinamide adenine di...