Homologous scries

The reaction of ChE s of different origin towards a homologous scries of choline esters permits a further classification within this group. This is exemplified in Fig. 1 for two representative types, the true ChE from the electric organ of Electrophorus electricus and the pseudo ChE from human plasma, both acting on acetylcholine as substrate. The curves show hydrolytic rates as function of pS = —log (substrate concentration) and demonstrate a fundamental difference between the two enzymes The true type exhibits a bell-shaped pactivity curve, indicative of autoinhibition at high substrate concentrations (18). The pseudo enzyme, on the other hand, possesses a tS-shaped curve i.e., the maximum rate is reached at and beyond an optimal substrate concentration. 

The table shows the formula of the first three members of the alcohol homologous scries. 

A universal system for qualitative identification was devised by Kovats some years ago. Based on the linear relation between log t K and the number of carbon atoms for a homologous scries, Kovats selected n-alkanes as standards for the following reasons ... 

In the study of emulsion polymerization kinetics which depend on monomer polarity, the homologous scries of alkyl acrylates and alky] methacrylates are usually used because of thcir wide ranges of solubility in... 

Compounds of metals and alkyl or aryl groups are frequently spontaneously ignitible in air, especially the lower members of homologous scries, such as the methyl and ethyl compounds. The metals in the most active compounds are the alkali metals and aluminum, zinc, and arsenic. The nonmetals boron and phosphorus also furnish active members, which conventionally are classed with the metal-organic (sometimes called organo-metallic) compounds. It is noteworthy that the alkyls of silicon do not flame in air. 

L Bata, A. Buka, N. fiber, A. Jfkii, X Pintdr, J. Szabon, and A. Vkjda. Properties of a homologous scries of ferroelectric liquid crystals, MoL Cryst Uq. Cryst 151 47 (1987). 

The reader will note that we avoided mention of the n — 0 species and the difference of their enthalpies of formation and those with n = 1. For the gas phase Me2N(CH=CH) CHO scries, the difference is 87.7 kJmol while for the H(CH=CH) H series it is 52.5 kJ mol . For the liquid phase Mc2N(CH=CH) CHO series, the difference is 64.3 kJ mol , while for the solid phase Ph(CH=CH) Ph and PhN=CH(CH=CH) NHPh series, they are now 8 and 37.5 kJ mol , A pattern is not particularly obvious—then again we have included real amides and amidines, biphenyl that wants to be twisted and diatomic hydrogen. Perhaps we have taken chemical homology and analogy too far. 

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