A Study of Absorption Mechanism of Amino Acids through Intestinal Wall

　1．In vitamin B₆ deficiency induced by L-penicillamine in vivo, the rate of absorption of L-amino acids is decreased but can be restored to the normal rate by the addition of vitamin B₆．The rate of absorption of D-isomer is far less than that of L-isomer and cannot be accelerated by the presence of vitamine B₆．

　2．Using the in vivo method, it was demonstrated that L-amino acids were actively transported from mucosal side of intestine, and evidence was presented that pyridoxal phosphate may play an important role in its active transport．

　3．With C¹⁴-glucose or C¹⁴-alanine, the rate of contribution of endogenous pyruvate to the transfered alanine was determined and it was found that over twenty percent of the transported alanine was derived from endogenous pyruvate, while in the presence of glutamate the amount originated from endogenous pyruvate increased up to over sixty percent．

　4．The in vitro experiments with heavy water, revealed that α and β hydrogens of the alanine transported was found to be replaced by deuterium, in spite of that the contribution of endogenous pyruvate was minimized within ten percent by avoiding the addition of glucose in the medium．

　5．From the above findings, it was assumed that the alanine transported was subjected to form Sciffbase with pyridoxal phosphate, through double transamination or some other reactions associated with this coenzyme．