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CINETICO [1 record]

Filter results by subject field Alphabetical list of terms

Filter results by subject field

Alphabetical list of terms

Record 1 2011-08-09

English

Subject field(s)
  • Biological Sciences
  • Biotechnology
DEF

A constant of great practical importance since it is equal to the substrate concentration required to reach half the maximum velocity. This constant of a substrate is therefore, a measure of the affinity of the enzyme for that substrate: the lower the constant, the higher the affinity. The constant possesses the unit gram molecule per liter (M) and it is independent of enzyme concentration. Kinetically, it is related to a number of rate constants. Values are usually in the range of 10-[supercript2]M to 10[Supercript 6)M.

CONT

A landmark paper has been published by Winter et al. (1982) on the redesigning of enzyme structure by site directed mutagenesis.... This is a method for systematically replacing (during biosynthesis) an amino acid at a particular site with another amino acid, and observing the consequences. In the quoted text, a reduction in enzymic activity was observed that was largely due to a lowered Michaelis constant (Km) for the ATP required to join the tyrosine to the transfer RNA.

OBS

The Michaelis constant determined for immobilized enzymes is necessarily only an apparent constant (K'm) and should be distinguished clearly from the constant normally determined with the soluble enzyme.

OBS

The term Km should read Km.

French

Domaine(s)
  • Sciences biologiques
  • Biotechnologie
DEF

Constante de cinétique enzymatique représentant la concentration de substrat pour laquelle la vitesse d'activité enzymatique est la moitié de la vitesse maximale. Elle s'exprime en mole/litre et définit bien l'affinité de l'enzyme pour son substrat. Elle varie avec chaque enzyme et suivant les conditions expérimentales (pH, nature du substrat).

CONT

La constante de Michaelis d'une enzyme est d'autant plus basse que l'enzyme est plus active, puisqu'elle exprime approximativement l'inverse de l'affinité du substrat pour l'enzyme. [...] La connaissance de la Km d'une enzyme est importante car une enzyme à Km élevée ne pourra agir avec efficacité dans la cellule que si le substrat s'y trouve à concentration élevée.

OBS

Le terme Km s'écrit Km.

Spanish

Campo(s) temático(s)
  • Ciencias biológicas
  • Biotecnología
DEF

Parámetro cinético de una enzima cuyo inverso da en ocasiones una medida de la afinidad entre sustrato y enzima.

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