Protein sequences from genes

Protein phosphatases 544, 646 Protein S 634 Protein sequenators 118 Protein sequences from genes 119 Protein synthesis 3, 538, 539 Protein tyrosine kinases 544 Protein-disulfide isomerase 83 Protein-DNA interactions 266 Proteinase. See Protease Proteoglycan(s) 181,182. See also Glycosami-noglycans... 

The MoFe-protein is an a2 2 tetramer (with the subunits coded by the nifD and nifK genes, respectively), with a total molecular weight of 240,000. The two subunits are of similar size for example, the isolated a and /3 subunits of A. vinelandii MoFe-protein have 491 and 522 amino acids, respectively (46). In general, the amino acid sequences of MoFe-proteins are less well conserved than are Fe-protein sequences, so that the MoFe-protein sequences from A. vinelandii and C. pasteuria-num are only 36% identical (47). Associated with the MoFe-protein tetramer are approximately 2 molybdenum atoms, 30 iron atoms, and 30 sulfur atoms that are organized into two types of metal centers the FeMo-cofactor and the P-cluster pair. The structures and properties of these centers have been extensively probed by a wide variety of techniques. 

The amount of sample required is quite small as little as 10 mole is typical So many peptides and proteins have been sequenced now that it is impossible to give an accurate count What was Nobel Prize winning work m 1958 is routine today Nor has the story ended Sequencing of nucleic acids has advanced so dramatically that it is possible to clone the gene that codes for a particular protein sequence its DNA and deduce the structure of the protein from the nucleotide sequence of the DNA We 11 have more to say about DNA sequencing m the next chapter... 

Section 28 11 Three RNAs are involved m gene expression In the transcription phase a strand of messenger RNA (mRNA) is synthesized from a DNA tern plate The four bases A G C and U taken three at a time generate 64 possible combinations called codons These 64 codons comprise the genetic code and code for the 20 ammo acids found m proteins plus start and stop signals The mRNA sequence is translated into a prescribed protein sequence at the ribosomes There small polynucleotides called... 

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