And don't forget biotin, essential for metabolism.
The biotin enzyme first undergoes a reaction that results in the attachment of carbon dioxide to biotin; ATP is required and forms ADP and inorganic phosphate [62a].
R. stolonifer is used to produce fumaric acid, lactic acid, and cortisone, and R. delemar produces fumaric acid and biotin.
Thiamin, riboflavin, vitamin B6, vitamin C, pantothenic acid, and biotin appear in urine as free vitamins (rather than as coenzymes); however, little free niacin is excreted in the urine.
In animal products (e.g., meat), biotin, vitamin B6, and folic acid are bound to other molecules to form complexes or conjugated molecules; although none is active in the complex form, the three vitamins normally are released from the bound forms by the enzymes of the intestinal tract (for biotin and vitamin B6) or in the tissues (for folic acid) and thus can be utilized.
Some folic acid and biotin also are normally excreted in this way.
The alga may provide the fungus with vitamins, especially biotin and thiamine, important because most lichen fungi that are grown in the absence of algae have vitamin deficiencies.
The most important biologically occurring thiophene derivative is the B-complex vitamin biotin.
The water-soluble vitamins are vitamin C (ascorbic acid) and the B vitamins, which include thiamin (vitamin B1), riboflavin (vitamin B2), vitamin B6, niacin (nicotinic acid), vitamin B12, folic acid, pantothenic acid, and biotin.
The complex product, called carboxybiotin enzyme, releases the carboxy moiety to acetyl coenzyme A, forming malonyl coenzyme A and restoring the biotin enzyme [62b].
This is also true of the ciliate protozoan Paramecium, which accumulates in areas with high concentrations of folate or biotin compounds that are released by bacteria, the food of these animals.
