Amino Acid Sequence of an Enzyme

Reflect and Apply Amino acids that are far apart in the amino acid sequence of an enzyme can be essential for its catalytic activity. What does this suggest about its active site ... 

Modification of the Amino Acid Sequence of an Enzyme 23 7 lAA Transforming DNA Constructs Obtained by Template-Free... 

If the amino acid sequence of an enzyme is known either entirely or even in part, computer-assisted calculations can provide estimated three-dimensional structures of enzymes [336]. This is done by comparing the known parts of the enzyme in question with other enzymes whose amino acid sequence and three-dimensional structures are already known. Depending on the percentage of the homology, i.e., overlap , of the amino acid sequences, the results are more or less certain. In general, an overlap of about 60% is sufficient for good results less is considered too inaccurate. 

Fig. 22.3 Cytochrome P450 monooxygenases and nicotine metabolism. An alignment of the amino acid sequences of the enzymes 2A6 and 2D6. Occurrences of the same amino acid residue at the same position are shown in black. Putative substrate recognition sites (SRS1—...

The three-dimensional and primary structures of the closely related enzyme, tyrosine phenol-lyase, have recently been determined.28 Since 43% of the amino acid sequences of this enzyme and tryptophanase is identical, their three-dimensional structures should be very similar. The structure of the lyase is like a butterfly. The tetrameric molecule can be considered from a crystallographic point of view as an a2a 2-structure consisting of two... 

For many applications it is important to know what the loading actually is (e.g. to compare activity of different enzymes immobilized to the same loading). Loading determination of an immobilized enzyme is often possible by methods such as quantitative amino acid analysis or active site titration. The latter has the advantage that only active enzyme is quantified. Typically, however, loading is determined indirectly during the immobilization process by measuring enzyme concentration in the aqueous solution before and after incubation with the carrier. The concentration of a pure enzyme in aqueous buffer can be determined from the absorption at 280 nm. The specific absorption can be calculated from the amino acid sequence of the enzyme. For less pure enzyme solutions, the total protein content can be determined with Bradford, BCA or other assays. 

Snake venoms, particularly those from North American pit vipers, contain direct-acting fibrinolytic proteinases (13). Fibrolase is the fibrinolytic enzyme from southern copperhead venom (14). Fibrolase is a non-glycosylated metalloproteinase with a molecular weight of 23,000 it contains one mole of zinc per mole of protein (14). The enzyme has an isoelectric point of approximately pH 6.8. The amino acid sequence of the enzyme has been determined... 

Determination of the Amino Acid Sequence of a Novel Protein Using LC-MS Data from an Enzyme Digest 160... 

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