This volume includes chapters on the newest techniques for measuring metabolites of branched-chain amino acids, many new enzyme assays such as the measurement of isozymes of acetohydroxacid synthase, and the purification of recently described enzymes such as isovaleryl-CoA dehydrogenase.Analytical and Synthetic Methods: G. Livesey and P. Lund, Determination of Branched-Chain Amino and Keto Acids with Leucine Dehydrogenase. S.J. Yeaman, K.G. Cook, A.P. Bradford, and S.M.A. Jones, Analysis of Phosphorylation Sites on Branched-Chain 2-Ketoacid Dehydrogenase Complex. D.J. Aberhart and J.-A. Cotting, High-Performance Liquid Chromatographic Separation of (3R) and (3S)-/-Leucine Using Marfey's Reagent. D.J. Aberhart, High-Performance Liquid Chromatographic Separation of ~ga- and /-Leucine. A.L. Gasking, W.T.E. Edwards, A.H. Frohock, M. Elia, and G. Livesey, Quantitative High-Performance Liquid Chromatographic Analysis of Branched-Chain 2-Keto Acids in Biological Samples. O.A. Mamer and J.A. Montgomery, Determination of Branched-Chain 2-Hydroxy and 2-Keto Acids by Mass Spectrometry. P.L. Crowell, R.H. Miller and A.E. Harper, Measurement of Plasma and Tissue Levels of Branched-Chain ~ga-Keto Acids by Gas-Liquid Chromatography. J.A. Montgomery and O.A. Mamer, Determination of Methylmalonic Acid in Biological Fluids by Mass Spectrometry. B.E. Corkey, Analysis of Acyl Coenzyme A Esters in Biological Samples. M.T. King, P.D. Reiss, and N.W. Cornell, Determination of Short-Chain Coenzyme A Compounds by Reversed-Phase High-Performance Liquid Chromatography. K. Bartlett and A.G. Causey, Radiochemical High-Performance Liquid Chromatography Methods for the Study ls+