Cathepsin substance

This protocol clearly indicates that identification of unknowns and related substances often demands data from a variety of MS instruments. The power of Q-LIT, providing triple-quadmpole MS-MS and MS in the LIT, for fragmentation smdies was promoted [49]. The complementary character of ion-trap and Q-TOF has been evaluated in a smdy on the in vivo metabolism of an cathepsin K inhibitor (NVP-AAV490) in the rat [50]. Some of the remaitung questions may be solved by additional tools outlined below. 

Several assays, such as the ultra-sensitive luminescent ELRA developed by Seifert (2004) with a detection limit of 20 ng L-1 for 17 (3-estradiol, have been reported in the literature. Although these assays are simple to use, many factors, such as differences in culture conditions, cell density or cell-line clones, affect the potency of estrogenic substances, and that makes the standardization of these methods difficult. The induction of several proteins or enzyme activities (e.g. the increasing levels of alkaline phosphatase, cathepsin D, prolactin and vitellogenin as a consequence of progestogens) has also been used to study estrogenicity. However, expression of these proteins or enzyme activities is restricted to specific cell lines and cannot be extrapolated to other tissues or species. 

C34Hg3N509, Mr 685.90, A -acylated peptide isolated from culture broths of various streptomycetes (Strep-tomyces testaceus, S. argenteolus) needles, mp. 228-229 °C (decomp.). The substance acts as an inhibitor of aspartate proteinases (caiboxy proteinases), e. g.,pepsin, cathepsin D (a lysosomal protease), and is also active against renin, formed in excessive amounts in some forms of kidney disease. There are also the pepstatins B and C, containing an A(-hexanoyl or N- A-methylpentanoyl) group, respectively, in place of the AT-(3-methylbutanoyl) group. 

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