Search results
Results from the WOW.Com Content Network
A protease (also called a peptidase, proteinase, or proteolytic enzyme) [1] is an enzyme that catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. [2] They do this by cleaving the peptide bonds within proteins by hydrolysis, a reaction where water ...
Photosystem II (of cyanobacteria and green plants) is composed of around 20 subunits (depending on the organism) as well as other accessory, light-harvesting proteins. Each photosystem II contains at least 99 cofactors: 35 chlorophyll a, 12 beta-carotene , two pheophytin , two plastoquinone , two heme , one bicarbonate, 20 lipids, the Mn
The antenna complex contains hundreds of chlorophyll molecules which funnel the excitation energy to the center of the photosystem. At the reaction center, the energy will be trapped and transferred to produce a high energy molecule. [2] The main function of PSII is to efficiently split water into oxygen molecules and protons.
Antenna molecules can absorb all wavelengths of light within the visible spectrum. [12] The number of these pigment molecules varies from organism to organism. For instance, the cyanobacterium Synechococcus elongatus ( Thermosynechococcus elongatus ) has about 100 chlorophylls and 20 carotenoids, whereas spinach chloroplasts have around 200 ...
Aspartyl proteases are a highly specific family of proteases – they tend to cleave dipeptide bonds that have hydrophobic residues as well as a beta-methylene group. Unlike serine or cysteine proteases these proteases do not form a covalent intermediate during cleavage. Proteolysis therefore occurs in a single step.
Hydrolase enzymes are important for the body because they have degradative properties. In lipids, lipases contribute to the breakdown of fats and lipoproteins and other larger molecules into smaller molecules like fatty acids and glycerol. Fatty acids and other small molecules are used for synthesis and as a source of energy. [1]
Limited proteolysis of a polypeptide during or after translation in protein synthesis often occurs for many proteins. This may involve removal of the N-terminal methionine, signal peptide, and/or the conversion of an inactive or non-functional protein to an active one.
If the substrate is water then hydrolysis results; if it is an organic molecule then that molecule is transferred onto the first substrate. Attack by the second substrate forms a new tetrahedral intermediate, which resolves by ejecting the enzyme's nucleophile, releasing the second product and regenerating free enzyme.