Variants of chymosin with improved properties

An isolated chymosin polypeptide variant, wherein:

• (a) the isolated chymosin polypeptide variant has a specific clotting activity (IMCU/mg total protein) that is at least 70% of the specific clotting activity of isolated camel chymosin polypeptide having SEQ ID NO:4;
• (b) the isolated chymosin polypeptide variant cleaves β-casein with a frequency of less than 50% of the frequency of β-casein cleavage by the isolated camel chymosin polypeptide having SEQ ID NO:4, as determined by quantifying β-casein peptides obtained by incubating skim milk with the chymosin variant or the camel chymosin, wherein quantification is carried out by RP-HPLC coupled to an ESI-Q-TOF mass spectrometer;
• (c) the isolated chymosin polypeptide variant comprises an amino acid sequence comprising from 3 to fewer than 30 amino acid alterations as compared to the amino acid sequence of SEQ ID NO:
• 4;
• and
• (d) the isolated chymosin polypeptide variant comprises an L222V substitution relative to SEQ ID NO:4.