Protein Proteolysis

Rana, T.M., and Meares, C.F. (1991a) Iron chelate-mediated proteolysis protein structure dependence. J. Am. Chem. Soc. 113, 1859-1861. 

Carter, P., Nilsson, B., Bumier, J.P., Burdick, D. and Wells, J.A. (1989) Engineering subtilisin BPN for site-specific proteolysis. Proteins, 6, 240-248. 

Protein C functions as an anticoagulant by proteolytically inactivating two protein cofactors of blood coagulation, factors V and VIII.402 It too circulates in a zymogen form and is activated by limited proteolysis. Protein C appears to contain about 16 sites for Ca2+, all of equal affinity, while activated protein C binds about nine Ca2+. Conformational rearrangement during activation results in loss of binding sites. 

Polverino deLaureto, P., Frare, E., Gottardo, R., VanDael, H., andFontana, A. 2002. Partly folded states of members of the lysozyme/lactalbumin superfamily A comparative study by circular dichroism spectroscopy and limited proteolysis. Protein Sci 11( 12) 2932—2946. 

Pathways named with the suffix "lysis" are those in which complex molecules are broken down or "lysed" into smaller units. For instance, in glycogenolysis, glycogen is lysed into glucose subunits in glycolysis, glucose is lysed into two pyruvate molecules in lipolysis, tri-acylglycerols are lysed into fatty acids and glycerol in proteolysis, proteins are lysed into their constituent amino acids. 

Cell Disruption Intracellular protein products are present as either soluble, folded proteins or inclusion bodies. Release of folded proteins must be carefully considered. Active proteins are subject to deactivation and denaturation, and thus require the use of gentle conditions. In addition, due consideration must be given to the suspending medium lysis buffers are often optimized to promote protein stability and protect the protein from proteolysis and deactivation. Inclusion bodies, in contrast, are protected by virtue of the protein agglomeration. More stressful conditions are typically employed for their release, which includes going to higher temperatures if necessaiy. For native proteins, gentler methods and temperature control are required. 

Superficially, the lambda repressor protein is very different from lambda Cro. The polypeptide chain is much larger, 236 amino acids, and is composed of two domains that can be released as separate fragments by mild proteolysis. In repressor the domain responsible for dimerization is separate from the... 

The shell of all picomaviruses is built up from 60 copies each of four polypeptide chains, called VPl to VP4. These are translated from the viral RNA into a single polypeptide, which is posttranslationally processed by stepwise proteolysis involving viraily encoded enzymes. First, the polypeptide chain is cleaved into three proteins VPO (which is the precursor for VP2 and VP4), VPl and VP3. These proteins begin the assembly process. The last step of the processing cascade occurs during completion of the virion assembly the precursor protein VPO is cleaved into VP2 and VP4 by a mechanism that is probably autocatalytic but may also involve the viral RNA. VPl, VP2, and VP3 have molecular masses of around 30,000 daltons, whereas VP4 is small, being 7000 daltons, and is completely buried inside the virion. 

Proteolysis of this precursor yields the active form, aerolysiu, which is responsible for the pathogenic effects of the bacterium in deep wound infectious and diarrheal diseases. Like hemolysin, aerolysiu monomers associate to form heptameric membrane pores. The three /3-strands that contribute to the formation of the heptameric pore are shown in red. The N-terminal domain (residues 1-80, yellow) is a small lobe that protrudes from the rest of the protein. 

INSULIN. Some protein hormones are synthesized in the form of inactive precursor molecules, from which the active hormone is derived by proteolysis. For instance, insulin, an important metabolic regulator, is generated by proteolytic excision of a specific peptide from proinsulin (Figure 15.3). 

Eiweiss-. albuminous, albuminoid protein, -abbau, m. proteolysis, -abbauprodukt, n. protein decomposition product, eiweiss-kholich, a. albuminoid, -arm, a. poor in albumin or in protein. 

Eiweiss-spaltung, /. cleavage of albumin protein cleavage, proteolysis, -sparmittel, n. albumin sparer protein sparer, -stoff, m. albuminous substance, protein albumen albumin, -verbindung, /. albuminous compound, protein albuminate. 

In addition to protein proteolysis during mitosis, ubiquitin-mediated protein degradation ( ubiquitin/ proteasome) is also required at the G1 to S transition... 

The human genome contains more than 90 different DUBs. Besides cleaving ubiquitin from distinct substrates, DUBs are also responsible for the recycling of free ubiquitin from ubiquitin chains and processing of ubiquitin- or ubiquitin like precursor proteins. Certain DUBs are also associated with the proteasome in order to detach ubiquitin chains before proteolysis. 

Metalloproteinases are a subgroup of proteinases. They are responsible for the cleavage of peptide bonds within a protein (proteolysis). Metalloproteinases contain a metal ion in the active center and are divided into four subclasses dependent on their mechanism of catalysis. 

Disorders caused by misfolded mutant proteins that fail to pass the quality control system of the ER (e.g., mutations of the cystic fibrosis transmembrane regulator protein (CFTR) causing cystic fibrosis). The mutant proteins are retrotranslocated into the cytosol and finally subjected to proteolysis. In some... 

Vitamin B12 is special in as far as its absorption depends on the availability of several secretory proteins, the most important being the so-called intrinsic factor (IF). IF is produced by the parietal cells of the fundic mucosa in man and is secreted simultaneously with HC1. In the small intestine, vitamin B12 (extrinsic factor) binds to the alkali-stable gastric glycoprotein IF. The molecules form a complex that resists intestinal proteolysis. In the ileum, the IF-vitamin B 12-complex attaches to specific mucosal receptors of the microvilli as soon as the chymus reaches a neutral pH. Then either cobalamin alone or the complex as a whole enters the mucosal cell. 

A topical enzyme aids in the removal of dead soft tissues by hastening the reduction of proteins into simpler substances. This is called proteolysis or a proteolytic action. The components of certain types of wounds, namely necrotic (dead) tissues and purulent exudates (pus-containing fluid), prevent proper wound healing. Removal of this type of debris by application of a topical enzyme aids in healing. Examples of conditions that may respond to application of a topical enzyme include second- and third-degree bums, pressure ulcers, and ulcers caused by peripheral vascular disease An example of a topical enzyme is collagenase (Santyl). 

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