Transaminations with pyruvate and other α-keto acids

It was considered that limitations in analytical technique had previously directed attention largely to transamination reactions involving L-glutamate and a-oxoglutarate.By means of paper-partition chromatography (e.g.Consden, Gordon & Martin, 1944), other amino acid-a-keto-acid pairs could be studied for transamination.Results now presented show that in liver preparations of some animal species, L-a-amino acids other than L-glutamate will transaminate with a-keto acids other than a-oxoglutarate.Pyruvate especially has been investigated as an amino acceptor.Evidence is given that transaminations with pyruvate do not involve a-oxoglutarate-L-glutamate as an intermediate amino carrier.For the L-x-amino acids concerned, transamination with pyruvate takes place more readily than aerobic oxidation.A preliminary report of this work has been published (Rowsell, 1951). MATERIALS AND METHODS L-a-Amino acids, a-keto acids and tissue preparations usedwere obtained or made, in general, as described in the earlier paper (Rowsell, 1956).Pure sodium a-oxobutyrate and a-oxoisocaproate were generously provided by Dr A. Meister, Bethesda, U.S.A.When 5pd.samples of 0-05M L-alanine were run on paper chromatograms a trace ninhydrin-reacting impurity was observed, running just behind alanine in water-saturated phenol.This may have been threonine (see Dent, 1948).According to chromatograms other amino acids used were pure.Particle preparations were thoroughly washed, at least five times by redispersion and resedimentation at 10000 g in about 50 ml. of 01M phosphate, pH 7*7.Usually particles from each rat liver were finally made up to 20 ml. in the same buffer.The clarified supernatant measured 20-25 ml.