Efficiency of coupling

In some circumstances CR1 and CR3 may efficiently bind their ligands, but phagocytosis may not be initiated. As described above, pretreatment with PMA may increase the ability of neutrophils to ingest these bound particles. Several naturally-occurring molecules can also promote the ingestion of coated particles presumably, this is achieved via alterations in the efficiency of coupling of receptor occupancy to intracellular signalling systems. 

FIGURE 2.11 Structures and nomenclature of compounds that serve as auxiliary nucleophiles. Generation of activated esters. Substituted hydroxamic acids are sometimes added to carbodi-imides or other reactions to improve the efficiency of couplings. The additive suppresses side reactions by converting activated species into activated esters (see Section 2.10) before they have time to undergo secondary reactions, p(Me2SO) HOBt 9.30, HOAt 8.70. 

A carbodiimide is added to the two reacting species. The urea generated from dicyclohexylcarbodiimide is insoluble and voluminous, so it is often replaced by diisopropylcarbodiimide, which generates a soluble urea. The soluble carbodiimide ethyl-(3-dimethylaminopropyl)-carbodiimide hydrochloride (see Section 1.16) is suitable but expensive. Efficiency of coupling is greater in dichloromethane than in dimethylformamide. There is also the option of adding 1-hydroxybenzotriazole to minimize the side reactions of A-acylurca (see Section 2.12), cyano (see Section 6.15), and aspartimide (see Section 6.13) formation. 

A Thaler, D Seebach, FC Cardinaux. Lithium-salt effects in peptide synthesis. Part II. Improvement of degree of resin swelling and efficiency of coupling in solid-phase synthesis. Helv ChimActa 74, 628, 1991. 

Another approach to block copolymer is the mutual termination of a living cationic polymer with a living anionic polymer, but the efficiency of coupling is generally low because of proton transfer from the carbocation to the carbanion, resulting in two homopolymers instead of the block copolymer [Richards et al., 1978]. 

Experimental studies have documented changes in drug response caused by increases or decreases in the number of receptor sites or by alterations in the efficiency of coupling of receptors to distal effector mechanisms. In some cases, the change in receptor number is caused by other hormones for example, thyroid hormones increase both the number of 3 receptors in rat heart muscle and cardiac sensitivity to catecholamines. Similar changes probably contribute to the tachycardia of thyrotoxicosis in patients and may account for the usefulness of propranolol, a 3-adrenoceptor antagonist, in ameliorating symptoms of this disease. 

Check the efficiency of coupling by measuring the A280 of the ligand before and after coupling. Usually at least 80% of the ligand is bound to the matrix. 

The gross counting rate of the sample in W1 (i i) contains counts due to Sr and two contributions firstly, background measured in the blank vial (Rhu, i) and secondly, counts due to Sr and (C9o i), which have to be deduced. will be established by means of the counting efficiencies of couple Sr/ V in the two windows (t79o i nd 7790-2) of the sample net counting rate in W2 (R2 -Rss-i) (without the Sr contribution). 

Equation 7.10 predicts that in systems of low receptor density and/or efficiency of coupling (or for agonists of low intrinsic efficacy), conditions whereby no shift of the... 

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