There is also a variation by strain for requirements of riboflavin, pyridoxal and folic acid. The activity was appreciably restored by the addition of pyridoxal phosphate. It employs one cofactor, pyridoxal phosphate. Pyridoxal phosphate promotes decarboxylation of amino acids. In fact, heating NH3 and glycoaldehyde spontaneously forms a variety of pyridines, including pyridoxal. Pyridoxal phosphate is required as a coenzyme. It has 2 cofactors&colon; pyridoxal phosphate, and Potassium. A decarboxylase with cofactor pyridoxal phosphate (PLP) removes CO from 5-hydroxy-L-tryptophan to produce 5-hydroxytryptamine. All four transsulfuration enzymes require vitamin B6 in its active form (pyridoxal phosphate or PLP). SHMT is a pyridoxal phosphate (PLP) dependent enzyme. Pyridoxal phosphate is a prosthetic group of this enzyme. The trapped pyridoxine and pyridoxamine are oxidized to pyridoxal phosphate in the tissue. A good example is provided with pyridoxal phosphate, a form of vitamin B6. PLP is synthesized from pyridoxal by the enzyme pyridoxal kinase, requiring one ATP molecule. For example, "R138W" is known to disrupt to pyridoxal phosphate binding site.