BCH 4024 Lecture 4: L4
23 Jan 2019
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Document Summary
It all begins with the peptide bond. One h2o molecule is lost in forming a peptide bond. What remains of each aa is called a residue. In cells, peptide formation is catalyzed by ribosomes. Trna molecules carry amino acids to the ribosome. Peptides can also be made in the lab. Loading one amino acid at a time. Washing and deprotecting to generate newly reactive functional groups. Number of possible unique sequences is nothing short of mind-boggling. Total number of possible sequences = 20^n. 20 different aa"s possible at each position. N= number of residues within a peptide. Any group within a peptide bond cannot ionize. Allows the computation of the theoretical pi (isoelectric point) and mw (molecular weight) entries or for user entered sequences. Aa sequence is determined in 2 ways: Enzymatic/chemical fragmentation followed by fragment separation & automated sequencing. Enzymes can be used to fragment proteins. Cleaves on carboxyl side of arg and lys.
