Involved in an anaerobic respiration pathway that converts the sulfonate taurine (2-aminoethanesulfonate) to ammonia, acetate and sulfide. Catalyzes the oxidative deamination of alanine which regenerates pyruvate, the amino group acceptor for the taurine--pyruvate aminotransferase enzyme, and liberates ammonia. Can also catalyze the reverse reaction in vitro. Cannot use NADP(H)(+) as a substrate. To a lesser extent, is also able to deaminate L-2-aminobutyrate in vitro, and in the amination reaction the enzyme can utilize oxaloacetate and 2-oxobutyrate in addition to pyruvate. H2O + L-alanine + NAD(+) = H(+) + NADH + NH4(+) + pyruvate Optimum pH is 9.0 for reductive amination of pyruvate and pH 9.0-11.5 for oxidative deamination of alanine. Optimum temperature is 55-60 degrees Celsius for reductive amination and 50-55 degrees Celsius for oxidative deamination. But at 60 degrees Celsius an inactivation of the enzyme is observed after about 1 minute, while at 65 degrees Celsius the enzyme is inactive after about 10 seconds. Organosulfur degradation; alkanesulfonate degradation. Homohexamer. Up-regulated in the presence of taurine. Taurine is an abundant dietary and host-derived molecule whose metabolism to hydrogen sulfide (H2S) by members of the human gut microbiota has many prominent connections to host health and disease. The human gut bacterium and opportunistic pathogen Bilophila wadsworthia produces H2S when respiring sulfite (HSO3-) released from organosulfonate substrates such as taurine and isethionate. Belongs to the AlaDH/PNT family.