The GTPase-activating protein (GAP) stimulates the GTPase reaction of p21 by 5 orders of magnitude such that the k
cat
of the reaction is increased to 19 s
-1
. Mutations of residues in loop L2 ...(Gly-12 and Gly-13), in loop L2 (Thr-35 and Asp-38), and in loop L4 (Gln-61 and Glu-63) influence the reaction in different ways, but all of these mutant p21 proteins still form complexes with GAP. The C-terminal domain of the human GAP gene product, GAP334, which comprises residues 714 to 1047, is 20 times less active than full-length GAP on a molar basis and has a fourfold lower affinity. This finding indicates that the Ν terminus of GAP containing the SH2 domains modifies the interaction between the catalytic domain and p21.
Discussed are the binary quantifiers introduced by J. Higginbotham & R. May (see LLBA 16/4, 8205940) & the Absorption rule used by them to derive Logical Forms for Eng sentences expressing these ...quantifiers. An inference is drawn concerning Universal Grammar (UG) which, if correct, provides strong motivation for their analysis. The semantics for quantifiers derived from absorption are reviewed, & it is shown that, contrary to a basic claim by Higginbotham & May, these quantifiers do not generalize iterated application of standard quantifiers. In consequence, the inference concerning UG is not supported & the status of Absorption as a rule of UG is placed in doubt -- the consequences of these claims are explored for UG. A new type of binary quantifier is introduced which yields a better account of simple sentences with multiple occurrences of quantified NPs than the quantifiers presented by Higginbotham & May. However, the introduced quantifiers will not handle the crossing coreference of Bach-Peters sentences. It is concluded that the ability to interpret Bach-Peters sentences does not derive from (known) principles. References. Modified AA
Methylation of Dimedone Clark, Robin D.; Ellis, John E.; Heathcock, Clayton H.
Synthetic communications,
19/1/1/, Letnik:
3, Številka:
5
Journal Article
Recenzirano
In connection with our synthetic approach to pentacyclic triterpenes,
1
we have required substantial amounts of 2,5,5-trimethyl-1,3-cyclohexanedione (methyldimedone, 2), which is available by ...methylation of dimedone (
1
).
2
However, methylation may also afford the 2,2-dimethyl product
3
, the methyl ether
4
, and the C, O-dimethyl product
5
.
The failures of traditional target-species management have led many to propose an ecosystem approach to fisheries to promote sustainability. The ecosystem approach is necessary, especially to account ...for fisheryï¾-ecosystem interactions, but by itself is not sufficient to address two important factors contributing to unsustainable fisheries: inappropriate incentives bearing on fishers and the ineffective governance that frequently exists in commercial, developed fisheries managed primarily by total-harvest limits and input controls. We contend that much greater emphasis must be placed on fisher motivation when managing fisheries. Using evidence from more than a dozen natural experiments in commercial fisheries, we argue that incentive-based approaches that better specify community and individual harvest or territorial rights and price ecosystem services and that are coupled with public research, monitoring, and effective oversight promote sustainable fisheries.
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