Abstract: A reagent for proteolytic enzyme assays has the general formula ##STR1## where RCO-- is an enzyme reactive acyl, such as an amino acid, peptide or substituted amino acid or peptide. The reagent may by hydrolyzed by proteolytic enzymes and developed to form a distinctive color. The reagent may be formed by reacting RCOOH with N-hydroxysuccinimide to form the acyl N-hydroxysuccinimide ester. The ester may then be reacted to form the reagent.

Abstract: A reagent for proteolytic enzyme assays has the general formula ##STR1## where RCO-- is an enzyme reactive acyl, such as an amino acid, peptide or substituted amino acid or peptide. The reagent may be hydrolysed by proteolytic enzymes and developed to form a distinctive color. The reagent may be formed by reacting RCOOH with N-hydroxysuccinimide to form the acyl N-hydroxysuccinimide ester. The ester may then be reacted to form the reagent.

Abstract: A liquid .beta.-streptococcus selective medium for the growth and detection of .beta.-hemolytic streptococci without allowing the growth of enterococci and other non-.beta.-hemolytic streptococci, consisting essentially of 0.2-0.4 gm. pullulan as carbohydrate source based on 93-72 ml water, a protein source such as a combination of Proteose Peptone #3, (a dried meat digest) and Biosate (pancreatic digest of casein combined with yeast autolysate), an inhibitor of the growth of Pseudomonas, such as thallous acetate, an inhibitor of the growth of gram negative organisms other than Pseudomonas, such as nalidixic acid, an inhibitor of the growth of staphylococci such as Gentamycin, and reduced aniline blue indicator.