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The carboxypeptidase A family can be divided into two subfamilies: carboxypeptidase H (regulatory) and carboxypeptidase A (digestive). [1] Members of the H family have longer C-termini than those of family A, [2] and carboxypeptidase M (a member of the H family) is bound to the membrane by a glycosylphosphatidylinositol anchor, unlike the majority of the M14 family, which are soluble.
Carboxypeptidase A (CPA) contains a zinc (Zn 2+) metal center in a tetrahedral geometry with amino acid residues in close proximity around zinc to facilitate catalysis and binding. Out of the 307 amino acids bonded in a peptide chain, the following amino acid residues are important for catalysis and binding; Glu-270, Arg-71, Arg-127, Asn-144 ...
zinc dialkyl dithio phosphate (ZDDP), probably the most widely used [2] in formulated engine oils, also acts as a corrosion inhibitor and antioxidant Tricresyl phosphate (TCP), used for high-temperature operation, often used as an AW and EP additive in turbine engine lubricants, and also in some crankcase oils and hydraulic fluids
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Gear oil degradation and longevity can be measured by its TAN. Chemical structure of a zinc dialkyldithiophosphate, a typical antiwear agent found in many motor oils. Alkaline additives are used to neutralize the acids mentioned previously, and also help prevent the formation of sulfates in a working oil.
Oil-soluble organophosphates, with or without zinc, have excellent high-pressure and antiwear properties, and provide corrosion protection especially in presence of chlorinated hydrocarbons. Zinc dialkyldithiophosphates (ZDDP) start decomposing at 130-170 °C, while the activation temperature of tricresyl phosphate (TCP) typically exceeds 200 ...
Flaxseed oil: Unrefined: 107 °C: 225 °F [3] Grape seed oil: 216 °C: 421 °F Lard: 190 °C: 374 °F [5] Mustard oil: 250 °C: 480 °F [11] Olive oil: Refined: 199–243 °C: 390–470 °F [12] Olive oil: Virgin: 210 °C: 410 °F Olive oil: Extra virgin, low acidity, high quality: 207 °C: 405 °F [3] [13] Olive oil: Extra virgin: 190 °C: 374 ...
Oil in this condition, just sitting in an engine, can cause problems. Also important is the quality of the oil used, especially with synthetics (synthetics are more stable than conventional oils). Some manufacturers address this (for example, BMW and VW with their respective long-life standards), while others do not.