title: Kinetic parameters governing the formation of eIF-2.methionyl-tRNAi complexes in protein synthesis.
abstract: Published data have been analysed to determine the rate constants governing the exchange of GDP in the complex of the eukaryotic protein synthesis initiation factor eIF-2 with GDP, catalysed by eIF-2B. The interaction of eIF-2B with eIF-2.GDP appears to include a very high 'on' rate constant of up to 4 x 10(8) M-1 sec-1 - a value very similar to that found by others for the interaction of the bacterial elongation factors Tu and Ts. Assuming a substituted enzyme mechanism that leads to displacement of GDP and ultimately to formation of a quaternary complex eIF-2B.eIF-2.GTP.methionyl-tRNA, minimum rate constants have been estimated for the additional reactions assuming in vivo rates of protein synthesis. Rate constants for the other reactions are unexceptional.
authors.affiliation: Department of Biochemistry, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: K L
authors.initials: KL
authors.lastname: Manchester
authors.forename: P
authors.initials: P
authors.lastname: Stasikowski
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D014176:Protein Biosynthesis; D012345:RNA, Transfer, Amino Acid-Specific / Q000378:metabolism*; D012358:RNA, Transfer, Met / Q000378:metabolism*
chemical_list: D015852:Eukaryotic Initiation Factor-2; D006150:Guanine Nucleotides; D012345:RNA, Transfer, Amino Acid-Specific; D012358:RNA, Transfer, Met; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate