Polar cod

Abbreviations acac. Acetyl acetonate AIBN, 2,2-azobis(isobutyro) nitrile bae, dianion of A,iV -ethylenebis(acetylacetoneimine) bdhc, 1,19-dimethyl-AD-bisdehydrocorrinato bdm 1,3 pn, bis(l,3-diacetylmonoximeimino)propane bipy, bipyridyl Bz, Benzyl CIDNP, chemically induced dynamic nuclear polarization cod, cyclooctadienyl COD, cyclooctadiene Cp, Cp, ij-CsMes CT, charge transfer diphos, P(Ph)2CH2CH2P(Ph)2 dmgH,... 

From Table I it can be seen that fish serum from cold ocean waters may have freezing temperatures as low as — 1.4°C, but not as low as those containing the antifreeze glycoproteins. The fish with freezing temperatures only as low as — 1.4°C were found in the Arctic south of the iceberg latitudes. The polar cod, containing the antifreeze glyco-... 

The polar cod frequents the far north Atlantic Ocean, the Barents Sea, and the Arctic Ocean, and, as such, and as its name implies, it is truly a polar fish. It is not surprising then that, when four species of fish were caught in the Barents Sea with temperatures varying from - 1.2°C to — 1.3°C at 79° N and 10-40 miles south of the southern end of a loose ice pack (frequent, but separated, small icebergs), only the polar cod was found to contain an antifreeze protein (Osuga and Feeney, 1978). This area would represent the near northern latitudes where the other three fish would go at that time and ocean temperature, while the polar cod is also found in more northern waters. 

Initial studies on the polar cod blood serum have shown that its antifreeze protein is a glycoprotein with most properties similar to those from the Antarctic species T. borchgrevinki. Both active and inactive components were obtained. The active components had the same ratios of alanine to threonine (approximately 2 1) as found in the Antarctic glycoproteins and the same contents of galactosamine and galactose. No other amino acids were found. In contrast to the comparatively low antifreeze activity of the saffron cod reported by Raymond and co-workers, the AFGP from the polar cod had an antifreeze activity similar to that from the Antarctic species. 

The glycoproteins from the Antarctic fishes and the Arctic polar cod have repeated amino acid sequences of Ala-Ala-Thr in their backbone polypeptide structure. Furthermore, disaccharide groups are regularly attached to all the threonine residues through a link-... 

The existence of an antifreeze-like substance in northern polar fish has been confirmed more recently by Scholander and Maggert (15), Hargens (16), and Raymond et al. (17), who found it in the saffron cod, Eleginus gracilis. An antifreeze substance also has been reported in the winter flounder (Pseudopleuronectes americanus) (18,19,20). Our laboratory recently has found antifreeze glycoproteins in the polar cod (Boreogadus saida) from the Barents Sea north of Russia (10). 

Lonne, O. J. and B. Gulliksen. 1989. Size, age and diet of polar cod, Boreogadus saida (Lepechin 1773), in ice covered waters. Pol. Biol 9 187-91. 

Toxaphene accumulates in tissues of many aquatic species, especially in lipid-rich tissues of polar fish and marine mammals (Swackhamer and McConnell 1993). Toxaphene concentrations in livers of Arctic fishes of 2.9 mg/kg FW and in Canadian cod liver oil of 28 mg/kg FW are recorded... 

A representative gas chromatogram with ECD of the analysis of various polar chlorinated pesticides isolated from cod liver oil [179] is shown in Fig. 13. Determination of the polar chlorinated pesticides in cod liver oil required clean up of the lipid matrix with a dimethylformamide/water/hexane liquid-liquid partitioning procedure followed by isolation using a normal-phase LC procedures, and final analysis by GC-ECD [179]. 

Fig. 13. A GC-ECD chromatogram of polar pesticide fraction analyzed in cod liver oil. Column 60-m capillary column with 5% phenyl-substituted methylpolysiloxane phase (after [179] with permission)...

Various PCB congeners and lower polarity pesticide fractions analyzed from cod liver oil is shown in Fig. 15 [179]. Measurement of the PCB congeners and pesticides in the cod liver oil required clean-up of the lipid matrix with a di-methylformamide/water/hexane liquid-liquid partitioning procedure followed by isolation of the PCBs and pesticides using a normal-phase LC procedures. The normal-phase LC procedures separate the analytes into two fractions, one containing the PCBs and the lower polarity chlorinated pesticides (HCB, 2,4 -DDE, and 4,4 -DDE) (Fig. 15) and the second containing the more polar chlorinated pesticides. The separation of PCBs and pesticides reduces the possible coelution of many of the pesticides with PCB congeners of interest. These two fractions were then analyzed by GC-ECD. 

The sol-gel entrapment of the metal complexes [Ru(p-cymene)(BINAP)Cl]Cl and the rhodium complexes formed in situ from the reaction of [Rh(COD)Cl]2 with DlOP and BPPM has been reported by Avnir and coworkers [198]. The metal complexes were entrapped by two different methods the first involved addition of tetramethoxysilane to a THF solution of the metal complex and triethylamine, while the second method was a two-step process in which aqueous NH4OH was added to a solution of HCl, tetramethoxysilane and methanol at pH 1.96 followed by a THF solution of the appropriate metal complex. The gel obtained by each method was then dried, crushed, washed with boiling CH2CI2, sonicated in the same solvent and dried in vacuo at room temperature until constant weight was achieved. Hydrogenation of itaconic acid by these entrapped catalysts afforded near-quantitative yields of methylsuccinic acid with up to 78% e.e. In addition, the catalysts were found to be leach-proof in ethanol and other polar solvents, and could be recycled. 

Delivery of hydrogen occurs syn to the polar functional group. Presumably, the stereoselectivity is the result of coordination of iridium by the functional group. The crucial property required for a catalyst to be stereodirective is that it be able to coordinate with both the directive group and the double bond and still accommodate the metal hydride bond necessary for hydrogenation. In the iridium catalyst illustrated above, the cycloocta-diene (COD) ligand in the catalyst is released upon coordination of the reactant. 

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