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Proteolytic enzymes
About: Proteolytic enzymes is a research topic. Over the lifetime, 23096 publications have been published within this topic receiving 835544 citations.
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TL;DR: This proteomic study enabled us to identify 392 nonredundant proteins and applied two alternative methodologies, off-line multidimensional protein identification technology and one-dimensional gel electrophoresis followed by proteolytic digestion and liquid chromatography coupled with tandem mass spectrometry (Gel-C-MS/MS), to identify envelope membrane proteins.
Abstract: With the completion of the sequencing of the Arabidopsis genome and with the significant increase in the amount of other plant genome and expressed sequence tags (ESTs) data, plant proteomics is rapidly becoming a very active field. We have pursued a high-throughput mass spectrometry-based proteomics approach to identify and characterize membrane proteins localized to the Arabidopsis thaliana chloroplastic envelope membrane. In this study, chloroplasts were prepared from plate- or soil-grown Arabidopsis plants using a novel isolation procedure, and “mixed” envelopes were subsequently isolated using sucrose step gradients. We applied two alternative methodologies, off-line multidimensional protein identification technology (Off-line MUDPIT) and one-dimensional (1D) gel electrophoresis followed by proteolytic digestion and liquid chromatography coupled with tandem mass spectrometry (Gel-C-MS/MS), to identify envelope membrane proteins. This proteomic study enabled us to identify 392 nonredundant proteins. K...
273 citations
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TL;DR: The X-ray study of synthetic polyamino acids is one of the possible approaches to the wider problem of the structure of natural proteins, with emphasis on α -amino acid residues in normal peptide linkage.
Abstract: Publisher Summary Poly- α -amino acids are obtained by the polymerization of amino acids or their suitable derivatives, serving as monomers. Like other synthetic polymers, they represent a mixture of macromolecules of varying chain lengths. This chapter deals with the synthetic poly- α -amino acids, with emphasis on α -amino acid residues in normal peptide linkage. Essentially, synthesis of poly- α -amino acids is accomplished by a typical one-step polymerization process in which a polymer of relatively high average molecular weight is obtained. The monomers used for synthesis of poly- α -amino acids include: (1) free α -amino acids, (2) esters of α -amino acids, (3) esters and azides of peptides, and (4) N-carboxy-α -amino acid anhydrides. The chapter also describes behavior of poly- α -amino acids toward proteolytic enzymes and the physical properties of poly- α -amino acids. Water soluble poly- α -amino acids are also presented. The X-ray study of synthetic polyamino acids is one of the possible approaches to the wider problem of the structure of natural proteins. Information about the packing arrangements of peptides can also be obtained by X-ray studies. Some polyamino acids can be cast into films or drawn into fibers, which helps in their study in oriented form and in addition allows a comparison of their properties with those of fibrillar proteins.
273 citations
TL;DR: Reticulocyte polyribosomes with labeled nascent chains were subjected to low-temperature proteolytic digestion by four different enzymes, and Pulse experiments showed that the most recently synthesized part of the chain was resistant to proteolysis, presumably because it is shielded by the ribosome.
273 citations
TL;DR: The synthesis of proteolytic enzymes by starter bacteria is a fundamental requirement for rapid acid production in milk fermentations as mentioned in this paper, and the strategic location of these enzymes, in the cell wall and membrane structures and in the cytoplasm, governs enzyme access to the substrates and is central to both roles.
Abstract: The synthesis of proteolytic enzymes by starter bacteria is a fundamental requirement for rapid acid production in milk fermentations. These organisms possess a number of proteinases and peptidases which act in concert to hydrolyse milk protein to the free amino acids required for cell growth. The same enzymes have an important secondary role in cheese ripening contributing to rheological and organoleptic changes. A highly complex mixture of both enzymes and substrates is present. The strategic location of these enzymes, in the cell wall and membrane structures and in the cytoplasm, governs enzyme access to the substrates and is central to both roles. An overview of the above topics is presented.
273 citations
TL;DR: An assay based on nucleic acid hybridization detects and quantitates hepatitis B virus (HBV) DNA in particles present in serum that correlates with infectivity of sera titered in chimpanzees as well as biophysical parameters and is in agreement with serological indicators of HBV presence.
Abstract: An assay based on nucleic acid hybridization detects and quantitates hepatitis B virus (HBV) DNA in particles present in serum. This assay allows rapid examination of multiple samples and is sensitive and reproducible; serum samples are treated with proteolytic enzyme and detergent and then extracted with phenol and chloroform. The deproteinized extracts which may contain HBV DNA are made alkaline to denature the DNA, neutralized, and bound to nitrocellulose filters in 3-mm in diameter “spots” in a special 96-well filtration apparatus. HBV DNA is detected by its ability to hybridize with 32P-labeled DNA prepared from recombinant plasmids containing the complete HBV genome. After hybridization, the nitrocellulose is washed and autoradiographed; samples containing HBV produce spots on X-ray film whose intensity (in the linear exposure range of the film) is proportional to the amount of HBV DNA in the serum sample. The assay is specific and sensitive, correlates with infectivity of sera titered in chimpanzees as well as biophysical parameters, and is in agreement with serological indicators of HBV presence.
272 citations