Production of industrially important enzymes by some actinomycetes producing antifungal compounds.

Seventeen strains of actinomycetes antagonistic to yeast and moulds have been tested for their ability to produce amylase, lipase, gelatinase and caseinase using solid media containing starch, Tween-20, gelatin and skimmed milk, respectively, Enzyme producing potential of test strains is expressed in ternis of relative enzyme activity (REA). Actinomycetes strain Streptomyces somaliensis GS 1242 and Streptomyces sampsonii GS 1322 showed higher amylase production (REA 6.5) while maximum lipase activity was noted in Streptomyces strain SAP 1089 (REA 7.0). Gelatinase activity was noted higher is S. sampsonii GS 1322 (REA 9.6) and S. somaliensis GS 1242 (REA 8.8). Enzyme producing potential of these strains has been discussed in terms of their industrial significance.

Characteristics of a 60K gelatinase involved in rat mammary gland involution.

In order to study the role of matrix degrading enzymes in modulating cell matrix interaction, an understanding of the characteristics and regulation of their activity is useful. A number of matrix degrading metalloproteinases are involved in modulating the cell-ECM interactions during the involutory phase of mammary gland resulting in its remodelling. Zymographic studies showed that three types of gelatinases (60K, 68K and 130K) occur during the different phases of involution. The 60K gelatinase which appeared on the fifth day of involution has been purified by affinity chromatography over gelatin sepharose. Zymographic and radiolabelled substrate digestion studies at different pH and in presence of different cations showed that the activated form of this gelatinase is a Ca2+ dependent neutral matrix metalloproteinase capable of cleaving collagen I and collagen IV. Immunocytochemical studies showed that the enzyme is localised at pericellular/extracellular sites.

Matrix metalloproteinases and lung injury

The dynamic equilibrium of extracellular matrix (ECM) under different physiological conditions is a consequence of the balance between the regulation of synthesis and degradation of ECM components. Matrix metalloproteinases (MMPs), a family of structurally related zinc-dependent endopeptidases, are the physiological mediators of matrix remodeling. The expression and activity of these enzymes are highly regulated at several intra- and extracellular levels, so that in vivo enzymatic activity is the final result of a complex series of events including gene expression, zymogen activation, matrix binding, and enzymatic inhibition. MMPs are expressed at low levels in normal adult tissues, and their upregulation appears to play an important role in the development of a number of pathological processes. In acute lung injury, a disorder characterized by a severe disruption of the gas exchange alveolo-capillary structures, the upregulation of interstitial collagenase and gelatinases A and B strongly suggests that MMPs contribute to acute lung damage by facilitating the migration of inflammatory cells, as well as to the disruption of basement membrane components and extracellular matrix remodeling.