TERMIUM Plus^®

Record 1,  Textual support,  English

Record number: 1, Textual support number: 1 CONT

The tools of contemporary molecular biology generate a bewildering prospect in that an astronomical number of single amino acid replacements can be generated in even a small enzyme containing only about 100 amino acid residues... Oligodeoxynucleotide-directed mutagenesis allows the systematic replacement of every single amino acid residue in a protein in turn... Since only a small subset of possible mutant proteins can be examined in the design and production of engineered proteins, target proteins must be carefully considered, and research must be guided by tools such as X-ray crystallography and molecular modeling. Clearly, however, the predictive power of X-ray diffraction techniques and molecular modeling will be much greater for some amino acid substitutions than for others. Mechanism-based inactivation of enzymes will be easy to predict given a known mechanism of action for an enzyme.  3, record 1, English, - amino%20acid%20substitution

Record 1,  Textual support,  French

Record number: 1, Textual support number: 1 CONT

L'ingénierie des protéines est l'ensemble des techniques qui permettent, si possible à partir de la connaissance de la structure tridimensionnelle des protéines, de fabriquer des protéines "sur mesure" entièrement nouvelles ou de remodeler d'une manière rationnelle et spécifique la structure des protéines naturelles afin d'améliorer leur fonction et rentabiliser ainsi leur emploi dans la technologie des aliments, ou les industries pharmaceutique et agrochimique. On peut, par exemple, modifier la stabilité thermique, la spécificité, l'activité, ou déplacer le pH optimum des enzymes. Au sens strict, la modification de la structure moléculaire (obtenue par substitutions d'acides aminés) se fait grâce aux modifications correspondantes au niveau des gènes par mutagénèse dirigée. Il faut souligner cependant que des protéines améliorées peuvent être obtenues également par la modification chimique des résidus d'acides aminés accessibles.  1, record 1, French, - substitution%20d%27acide%20amin%C3%A9

Record 1,  Textual support,  Spanish

Record 2,  Textual support,  English

Record number: 2, Textual support number: 1 DEF

Promotion of a chemical reaction by addition of a substance or enzyme (catalyst) that partakes in, but is not permanently affected by the reaction. In the case of enzymes, it is mediated by the functional groups found in amino acid side chains and coenzymes. Notably, the amino acid side chains of histidine, serine, cysteine, lysine, glutamate, and aspartate are frequently directly involved in the catalytic process. Coenzymes or metals work in conjunction with enzymes to provide a greater variety of functional groups than is available through amino acid side chains alone.  2, record 2, English, - catalysis

Record number: 2, Textual support number: 1 CONT

DNA technology enables the facile modification of proteins by highly specific mutagenesis of their genes. Enzymes with novel properties may be produced in large quantities from the mutant genes. Kinetic analysis of the mutant enzymes can be combined with high-resolution structural data from protein X-ray crystallography to provide direct measurements on the relationships between structure and function. In particular, the strength and nature of enzyme-substrate interactions and their roles in catalysis and specificity may be studied.  3, record 2, English, - catalysis

Record 2,  Textual support,  French

Record number: 2, Textual support number: 1 DEF

Accélération d'une réaction chimique grâce à la présence, en petite quantité, d'une substance (appelée catalyseur), qui est retrouvée inchangée à la fin de la réaction.  2, record 2, French, - catalyse

Record number: 2, Textual support number: 1 CONT

Certains enzymes subissent une activation irréversible quand ils sont traités par des agents capables de se fixer de façon covalente à un groupement fonctionnel indispensable à la catalyse, ce qui conduit à la formation d'une molécule enzymatique inactive.  3, record 2, French, - catalyse

Record 2,  Textual support,  Spanish

Record number: 2, Textual support number: 1 DEF

Proceso por el cual varía la velocidad de una reacción química por la presencia de una sustancia, el catalizador, que al finalizar la reacción permanece inalterada.  1, record 2, Spanish, - cat%C3%A1lisis