Purification of a neutral proteinase, associated with the actomyosin complex, from uterine myometrium

Cathepsin B, D and H activities in muscles of chicks of fast and slow growing strains: effect of age and diet

1. Activities of cathepsins B, D and H were measured in leg and breast muscles of fast growing (broiler) and slow growing (layer) chicks at eight time intervals between 1 and 29 days of age. 2. These enzyme activities were also measured in muscles from fast and slow growing chicks given a low protein (125 g/kg crude protein) diet between the ages of 17 and 24 days. 3. Activities of none of these cathepsins differed greatly between muscle type or strain of chick. However in both strains of chick cathepsin D and H in muscles significantly decreased with increasing age (muscle size) of the chick. Cathepsin D activity also increased when muscle proteolytic rates were increased by feeding a low protein diet. This latter effect was significant only in the muscles of fast growing chicks. 4. The results suggest that lysosomal proteases are not responsible for the differences in muscle protein degradation and growth between fast and slow growing strains of chicks, or between muscle types in the chick.

Separation and identification of two components of an estrogen-responsive, calcium-dependent arginine esteropeptidase

Arginine esteropeptidase is an estrogen-responsive, calcium-dependent enzyme in rat uterine cytosol. It appears in increased amounts 3 h after administration of physiologic amounts of 17 beta-estradiol to an immature female rat. Its reaction was resolved into two parts: a calcium-dependent activation of the enzyme and a calcium-independent hydrolysis of the substrate. The esteropeptidase was separated by DEAE cellulose chromatography into two components. The properties of component A, the activator, are distinct from those of component B, the enzyme, which has the same response to inhibitors as serine proteinases. Both components are subject to estrogen control. Component A is present in significant amounts only after estrogen stimulation. Component B is increased 3-fold after estrogen stimulation. The responses of the two components to inhibitors, their different molecular weights and chromatographic behavior and the pH optima of their reactions distinguish them from each other and from other uterine proteinases previously described.