Residue identification

This modification of the DMAA program permitted identification of the first 14 residues. Identification of the polar amino acids in positions 15 and 16 could not be achieved whereas glycine in position 17 could again be recognized. The remaining unknown section of the sequence was elucidated by the manual Edman degradation procedure after tryptic cleavage of C3... 

Additional analyses will normally be required in order to identify and quantify individual residues within a group of antimicrobials to determine whether a positive result exceeds the MRL level. For suspect penicillin residues, identification can be made by repeating the microbiological assay in the presence of -lactamase. If the inhibition zone disappears by this addition, penicillin residues are present in the sample. If not, no conclusion can be drawn because several new-generation -lactams are less sensitive to inactivation by -lactamase. 

The above brief review illustrates that chemical derivatization techniques have been used extensively for the confirmation of identity of organochlorine residues. In most instances, the lower limits of detectability of the derivatives are substantiaUy lower than the established tolerance values for the parent compounds. Taken in conjunction with the many other modes of derivatization—e.g., during or after gas chromatography (59)— the analyst has a vast array of modification procedures at hand to aid in residue identification. They can be employed for residues in soil, biological, fat, and nonfat extracts and can be successfuUy extended, especially the more specific tests, to the identification of crosscontaminants in pesticide formulations and also fertilizer mixtures. So far, these latter two cases have only been a fringe area of application (60,61). 

Applications of Combined Gas Chromatography—Mass Spectrometry to Pesticide Residue Identifications... 

The most practical approach is to first find out which method your sequencing laboratory favors. If the objective is to find a sequence for probe design, the didegeneracy of Cys codons makes positive identification of cysteine residues valuable. If the objective is just to identify the protein via a database search from directly sequencing the intact protein, positive identification of cysteine may be less essential as long as 8 to 10 cycles of unambiguous residue identifications can be made. 

Unfortunately, phosphothreonine, which also undergoes P-elimination and modification by ethanethiol, is converted to a derivative that presents analytical complications. Often, if it can be established that a phosphorylated protein contains only one type of phosphorylated residue, identification can be made on the basis that the... 

Composition of deposited layers Thickness of deposited layers Defect characterization Particle identification Process residue identification Lubricant type and thickness Carbon overcoat composition Magnetic layer composition Magnetic layer thickness Defect/contamination identification Failure analysis... 

Surface cleanliness Detergent residue identification Solvent residue identification Type and amount of surface impurities... 

Microelectronics Composition of deposited layers Thickness of deposited layers Defect characterization Particle identification Process residue identification... 

Detection of ignitable liquid residues Identification of explosive materials and examination of postexplosion exhibits... 

Adamovich TB, Pikuleva lA, Chashchin VF, Us-anov SA (1989) Selective chemical modification of cytochrome P-450SCC lysine residues. Identification of lysines involved in the interaction with ad-renodoxin. Biochim Biophys Acta 996 247-253... 

Malic enzyme, labeling of, 139 Mandelate racemase, 541-548 effect of metal ion on, 546, 547 residue identification, 547, 548 stoichiometry of binding, 545, 546 D-Mannitol, 384-386 Membrane, see abo specific type sodium channels, 288 transport, 167 Menadione, 76 Mercaptans, 317 2-Mercaptobenzothiazole, 540 Mercaptoethanol, 402, 451 6-Mercaptopurine, analogs of nucleotides, 289... 

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