sr-Methionyl Cow Alpha-S1-Casein is a single chain protein produced by fermentation in E. coli. The starting gene is synthetically produced to be identical to Alpha-S1-Casein which is found in the Bos taurus (cow) with the initiation code for methionine. The protein contains 214 amino acids which may contain disulfide bonds and/or glycosylation, and consists of the proper sequence of the 20 standard amino acids.