Digestives including enzymes

Merops (http //merops.sanger.ac.uk), database of peptidases and their proteinaceous inhibitors. Includes enzyme classification and nomenclature, external links to literature, and the structure of proteins of interest (if known). Enables one to find the gene coding for a given peptidase or to find the best enzyme to digest a chosen substrate. 

Drawing on this and the reported specificity of tannin-protein interactions ( ) leads to the conclusion that any useful in vitro modelling of the impact of tannins on digestion must consider more than pH and the concentrations of the buffer, enzyme, substrate, and tannin. The actual enzyme-substrate system must be nutritionally realistic to control for specificities of the reaction of tannins with proteins (including enzymes) gastrointestinal mucoproteins should perhaps also be included on the same grounds. Besides all this, misleading results nay still be obtained if bile surfactants are omitted from the equation. 

Barley is often considered to be somewhat prophylactic with regards to digestive disorder in piglets. This seems to be accentuated by including enzymes. This is presumably due to the enzymes stimulating digestion in the upper sections of the intestinal tract, which in trrm reduces readily available substrate for bacterial proliferation in the lower tract. 

With regard to immunosensors, a number of different reporter groups are used, including enzymes which convert a substrate into a highly coloured product (enzyme-linked immunosorbent assay, ELISA ) or which digest a substrate to give a photon of light to expose a film (chemiluminescence). 

The International Union of Biochemistry has recommended that enzymes have three names, namely a systematic name, which shows the reaction being catalysed and the type of reaction based on the classification in Table A7.1, a recommended trivial name and a four figure Enzyme Commission code (EC code). Nearly all systematic and trivial enzyme names have the suffix -ase. Systematic names show, often in semi-chemical equation form, the conversion the enzyme promotes and the class of the enzyme. Trivial names are usually based on the function of the enzyme but may also include or be based on the name of the substrate. However, some trivial names in current use are historical and bear no relationship to the action of the enzyme or its substrate, for example, pepsin and trypsin are the names commonly used for two enzymes that catalyse the breakdown of proteins during digestion. The Enzyme Commission s code is unique for each enzyme. It is based on the classification in Table A7.1 but further subdivides each class of enzyme according to how it functions. The full code is... 

Q14 Cystic fibrosis patients are usually prescribed pancreatic enzymes to aid digestion. Which enzymes are likely to be included in these preparations ... 

In addition to the enzyme described, many other exopeptidases are known. These include enzymes specific for peptides of D-amino acids, prolyl peptides, glutathione (y-glutamylcysteinylglycine), and alanyl peptides. It is of interest that many of the peptidases occur in tissues that are not concerned with digestion. It is therefore possible that they may be involved in specific syntheses as well as in degradations. 

---