The first step in the catabolism of amino acids is the removal of the nitrogen as ammonia, forming a keto Map acid that can enter one of the carbon catabolic pathways. The a-keto acid pyruvate can be formed from the amino acids alanine, cysteine, glycine, serine and threonine. Consider the route for alanine catabolism. Danine reacts with Select answer This reaction is catalyzed by to produce pyruvate and This reaction is catalyzed by aspartate aminotransferase. alanine aminotransferase. alanine dehydrogenase. The substrate for the first step can be regenerated by reacting Select answer Select answer glutamate dehydrogenase. a-ketoglutarate dehydrogenase. alanine dehydrogenase. aspartate dehydrogenase. The coenzyme/prosthetic group required in the first reaction is with NAD*. thiamine pyrophosphate. biotin. pyridoxal phosphate. O lipoic acid.