What type of protein is pepsin

Pepsin was the first animal enzyme to be discovered, and, in , it became one of the first enzymes to be crystallized, by John H. Pepsin was also the first crystallized protein to be studied by X-ray diffraction using the method of capillary mounting to prevent water loss [1].

Pepsin is one of three proteolytic, or protein degrading enzymes in the digestive system. It resides in the alimentary canal, and is produced by mucosal cells, as an inactive precursor pepsinogen.

Once it is secreted into the acidic conditions of the stomachs lumen, the propart peptide is cleaved, yielding the active pepsin. Pepsin degrades peptides, and is optimally active at low pHs [1]. Pepsin is an aspartic proteinase, more specifically a eukaryotic aspartic protease enzyme.

Pepsin was among the first enzymes to be isolated in crystalline form [2]. Aspartic proteinases are widespread in nature, and pepsin in particular has been known to be medically important [3]. Endothiapepsin ETPep hydrolyzes proteins with preference to hydrophobic residues at P1 and P1' positions. Pepsin is bilobal, and composed of two nearly equal N and C domains related by an intra dyad [2]. There are residues in pepsin, forming two topologically similar lobes.

Residues form the N-terminal lobe, and residues constitute the C-terminal lobe. A large portion of the residues are polar and buried [1]. All the a-helices except h'c are partially exposed and have some amphiphilic characteristics especially hc. Hc has a solvated surface and a buried side [1]. These sheets are related by an intra-lobe topological 2-fold symmetry.

Further, a six-stranded sheet spans the two lobes and forms a structure resembling an arch upon which the other four strands reside [1]. Fab fragments are generated by cleavage of IgG with papain instead of pepsin. Papain cleaves IgG above the hinge region containing the disulfide bonds that join the heavy chains, but below the site of the disulfide bond between the light chain and heavy chain.

This generates two separate monovalent containing a single antibody binding site Fab fragments and an intact Fc fragment. The fragments can be purified by gel filtration, ion exchange, or affinity chromatography. Fab and F ab' 2 antibody fragments are used in assay systems where the presence of the Fc region may cause problems. In tissues such as lymph nodes or spleen, or in peripheral blood preparations, cells with Fc receptors macrophages, monocytes, B lymphocytes, and natural killer cells are present which can bind the Fc region of intact antibodies, causing background staining in areas that do not contain the target antigen.

Use of F ab' 2 or Fab fragments ensures that the antibodies are binding to the antigen and not Fc receptors. These fragments may also be desirable for staining cell preparations in the presence of plasma, because they are not able to bind complement, which could lyse the cells. F ab' 2, and to a greater extent Fab, fragments allow more exact localization of the target antigen, i. The divalency of the F ab' 2 fragment enables it to cross-link antigens, allowing use for precipitation assays, cellular aggregation via surface antigens, or rosetting assays.

Protein Sci. PMC PMID Retrieved Current Protocols in Protein Science. Chapter Unit ISBN A short history of biology. Westport, Conn: Greenwood Press. Online Etymology Dictionary. The Quarterly Review of Biology. JSTOR Bibcode : Sci Lehninger principles of biochemistry. San Francisco: W. ISBN X. The Laryngoscope. The Annals of Otology, Rhinology, and Laryngology. Journal of Gastrointestinal Surgery. The American Journal of Gastroenterology. Gastroesophageal and pharyngeal reflux detection using impedance and hour pH monitoring in asymptomatic subjects: defining the normal environment.

J Gastrointest Surg ;— Otolaryngology—Head and Neck Surgery. International Journal of Otolaryngology. Advances in Experimental Medicine and Biology. Bibcode : PNAS The Scientific Monthly. Bibcode : SciMo.. Kinetic evidence for ordered release of products". Plant Extracts. Mushroom Extracts. Animal Extracts. Fruit Powder. Vegetable Powder. Vegetarian Protein. Other Products. Home Pepsin Pepsin. Pepsin is one of the principal protein degrading or proteolytic enzymes in the digestive system.

During the process of digestion, Pepsin acts on the complex dietary protein and breaks up into peptides and amino acids which can be readily absorbed by the intestinal lining.

It helps in digestive disturbance in general and as a result of impaired production of gastric juice. It acts as an adjunct in the treatment of anemic conditions, especially during slimming diet when protein intake increases. It is used as research tool in protein analysis and as digestive syrup in heart burn, acid indigestion and sour stomach. It is also used in tablets for increasing appetite and in the preparation of cheese and other protein-containing foods.

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