Some are better known by name than number&colon; niacin, pantothenic acid, biotin and folate. Organic prosthetic groups can be covalently bound (e.g., biotin in enzymes such as pyruvate carboxylase). BME contains biotin (vitamin B), which Eagle later found to be superfluous. Symptoms of biotin deficiency include alopecia and achromotrichia. Avidin biotin media is used in the purification process of biotin/avidin and their derivatives. Streptavidin is not the only protein capable of binding to biotin with high affinity. It is also important in freeing biotin from dietary protein-bound biotin. Pregnant women tend to have a higher risk of biotin deficiency. The probe is tagged directly with fluorophores, with targets for antibodies or with biotin. An alternative to primary amine biotinylation is to label sulfhydryl groups with biotin. This situation results in biotin deficiency. This process assists free biotin release from biocytin and protein-bound biotin. In this type of system biotin is coupled to the antibody. Other coenzymes, flavin adenine dinucleotide (FAD), biotin, and lipoamide, for instance, are tightly bound. Firstly, there is high shape complementarity between the binding pocket and biotin.