Enzymes, degradation extracellular

Matrix metalloproteinases Zinc-dependent enzymes capable of degrading extracellular matrix proteins, including connective tissue. 

The extracellular polysaccharides of Rhizobium meliloti 201 have been examined by using enzymic degradation and chemical procedures.314 A mixture of polysaccharides produced by the bacterium, when incubated with a bacterial enzyme that hydrolyzed one of these, gave oligosaccharides that could be separated by DEAE-cellulose chromatography. The major fraction was a pentasaccharide, for which methylation analysis and Smith... 

Chylomicrons are triglyceride rich and contain apolipoprotein B-48 and the A types. The latter are synthesized in the intestinal tract cells. Additional apoproteins are transferred to the chylomicrons from HDL in circulation the apoE and apoC types. Their site of synthesis is the liver. The chylomicrons are subject to degradation by lipoprotein lipase in the peripheral tissue, especially adipose tissue. Lipoprotein lipase activity is increased by increased blood insulin levels. This enzyme is extracellular, attached to the capillary endothelial cells, and activated by ApoC-II, which is present in the chylomicrons. Lipoprotein lipase causes the hydrolysis of triglycerides, thus decreasing chylomicron size... 

If the degrading enzyme is extracellular, the target bonds in the molecule must be exposed to this... 

Qiu WQ, Walsh DM, Ye Z, Vekrellis K, Zhang J, Podhsny MB, Rosner MR, Safavi A, Hersh LB, Selkoe DJ (1998) Insulindegrading enzyme regulates extracellular levels of amyloid beta-protein by degradation. J Biol Chem 273 32730-32738. 

Matrix metalloproteinases are a recently discovered class of zinc enzymes able to degrade extracellular matrix components. [Zn(OH)TpCum,Me)] has been reported to cleave activated amides and ester.130 The reaction of [Zn(OH)(TpPB,Me)] with acetohydroxamic acid has been also described,131 as well as protonolis of zinc thiolate bond in [Zn(SPh)(Tpph)].132... 

Human colonic bacteria are quite versatile with respect to their ability to ferment polysaccharides. Moreover, individual species do not seem to have a consistent strategy for degrading polysaccharides. In some cases, cell-associated periplasmic enzymes are used. In other cases the enzymes are extracellular or even membrane-bound. It may turn out to be the case that the catabolic strategy is specific for the type polysaccharide rather than for the species, i.e. different species may utilize a particular type of polysaccharide in the same way. 

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