Proteolytic enzymes

About: Proteolytic enzymes is a research topic. Over the lifetime, 23096 publications have been published within this topic receiving 835544 citations.

On the surface coat and flagellar adhesion in trypanosomes.

Abstract: Pathogenic trypanosomes in their bloodstream phase have a smooth and compact coat 12-15 nm thick enveloping the entire surface membrane of the body and flagellum. In the sleeping-sickness trypanosome Trypanosoma rhodesiense this coat is absent from the stages of development in the midgut of the tsetse-fly vector and from their counterparts obtained by cultivation of the trypanosome in vitro. In the salivary glands of the vector, however, the coat is reacquired as the trypanosomes transform from epimastigote forms into the metacyclic stage which is infective to the mammalian host. This loss and acquisition of the surface coat can be correlated with the cyclical changes in net surface charge on the trypanosome which have been observed by other workers. The trypanosome populations of successive relapses in the blood are known to differ in their surface antigens (agglutinogens) and the loss of antigenic identity detected when any of these populations are put into culture indicates that these variable antigens are located in the surface coat. It is suggested that the coat in bloodstream trypanosomes constitutes a replaceable surface which, after being replaced, enables the trypanosome to escape the effects of host antibodies. The coat is therefore an adaptation to life in the bloodstream. Reacquisition of the surface coat by the metacyclic trypanosome after development in the vector may reflect reversion to a ‘basic’ antigenic type at this stage, preparatory to invading the blood of the mammalian host. The surface coat may be removed by the wide-spectrum proteolytic enzyme pronase, and this fact together with evidence from pH/mobility relationships and chemical analysis of the variable antigens suggest that the coat is basically proteinaceous. The coat may facilitate pinocytosis by binding proteins at sites within the pocket surrounding the base of the flagellum. In the non-pathogenic trypanosome T. lewisi a more diffuse filamentous coat is present in bloodstream forms and absent from culture forms. This trypanosome is said to carry a negative charge in both bloodstream and culture phases, so it seems likely that the nature of the coat in T. lewisi is different from that found in the pathogenic trypanosomes. In all these trypanosomes the flagellar membrane adheres to the surface membrane of the body throughout the life-cycle. Along the zone of adhesion lies a regular row of junctional complexes of the macula adherens type which, it is argued, serve in attachment. These attachments persist regardless of changes in the intervening cell surfaces.

The use of proteolytic enzymes for the mapping of structural rearrangements in the chromosomes of man.

Abstract: Chromosome preparations treated for short periods with the proteolytic enzyme trypsin show well defined banding patterns, comparable to those obtained by more elaborate techniques.—With such patterns it is possible to map in detail the position of chromosome rearrangements.—A rare balanced A1–E18 translocation in a phenotypically normal female and the unbalanced product in her abnormal child has been used to demonstrate this mapping method.

Characterization of Exocellular Protein and Its Role in Bioflocculation

Abstract: The relationship between exocellular biopolymer concentration and cation concentration was examined using laboratory scale activated sludge reactors with bactopeptone as a feed. An increase in the divalent cation concentration in the feed to the reactors was associated with an increase in the bound exocellular protein concentration, and high sodium concentrations resulted in a decrease in the bound protein concentration. The changes in bound biopolymer were explained according to the cation bridging model. Incubation of a laboratory activated sludge with a proteolytic enzyme resulted in deflocculation of the suspension as measured by an increase in the number of particles in the 5–40 μm range, which suggested that the exocellular protein was strongly involved in the aggregation of bacteria into flocs. SDS PAGE results revealed the presence of a single protein in the exocellular biopolymer extract from municipal, industrial, and laboratory activated sludge samples. The molecular weight of the protein was approximately 15 daltons. Amino acid analysis and amino acid sequencing results suggested the protein was a lectinlike protein, and binding site inhibition studies demonstrated that the protein had lectinlike activity.

Preparation and hybridization analysis of DNA/RNA from E. coli on microfabricated bioelectronic chips

Abstract: Escherichia coli were separated from a mixture containing human blood cells by means of dielectrophoresis and then subjected to electronic lysis followed by proteolytic digestion on a single microfabricated bioelectronic chip. An alternating current electric field was used to direct the bacteria to 25 microlocations above individually addressable platinum microelectrodes. The platinum electrodes were 80 microns in diameter and had center-to-center spacings of 200 microns. After the isolation, the bacteria were lysed by a series of high-voltage pulses. The lysate contained a spectrum of nucleic acids including RNA, plasmid DNA, and genomic DNA. The lysate was further examined by electronically enhanced hybridization on separate bioelectronic chips. Dielectrophoretic separation of cells followed by electronic lysis and digestion on an electronically active chip may have potential as a sample preparation process for chip-based hybridization assays in an integrated DNA/RNA analysis system.