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Protoplast (from Ancient Greek πρωτόπλαστος (prōtóplastos) 'first-formed'), is a biological term coined by Hanstein in 1880 to refer to the entire cell, excluding the cell wall. [ 1 ] [ 2 ] Protoplasts can be generated by stripping the cell wall from plant , [ 3 ] bacterial , [ 4 ] [ 5 ] or fungal cells [ 5 ] [ 6 ] by mechanical ...
Protoplasm (/ ˈ p r oʊ t ə ˌ p l æ z əm /; [1] [2] pl. protoplasms) [3] is the part of a cell that is surrounded by a plasma membrane.It is a mixture of small molecules such as ions, monosaccharides, amino acids, and macromolecules such as proteins, polysaccharides, lipids, etc.
The active site of the enzyme is made up of beta-sheets five and 11, as well as alpha-helix 5, and four separate residue loop structures. [20] Within MTAP, helix six is a 12-residue C-terminal helix that arranges for the leucine residue 279 of one subunit to be a part of the active site of another subunit. [ 20 ]
Cystathionine beta-lyase is a tetramer composed of identical subunits, and is constructed as a dimer of dimers, each associated with one molecule of PLP bound to the catalytic site by a lysine residue.
An enzyme's specificity comes from its unique three-dimensional structure. IUPAC definition for enzymes. Like all catalysts, enzymes increase the reaction rate by lowering its activation energy. Some enzymes can make their conversion of substrate to product occur many millions of times faster.
6PGL in Homo sapiens exists as a monomer at cytosolic physiological conditions, and is composed of 258 amino acid residues with a total molecular mass of ~30 kDa. [7] The tertiary structure of the enzyme utilizes an α/β hydrolase fold, with both parallel and anti-parallel β-sheets surrounded by eight α-helices and five 3 10 helices. [1]
Double-stranded DNA phage lysins tend to lie within the 25 to 40 kDa range in terms of size. A notable exception is the streptococcal PlyC endolysin, which is 114 kDa. PlyC is not only the biggest and most potent lysin, but also structurally unique since it is composed of two different gene products, PlyCA and PlyCB, with a ratio of eight PlyCB subunits for each PlyCA in its active conformation.
In structural biology, a protomer is the structural unit of an oligomeric protein. It is the smallest unit composed of at least one protein chain. The protomers associate to form a larger oligomer of two or more copies of this unit. Protomers usually arrange in cyclic symmetry to form closed point group symmetries.