lecturenoteschap3-10-2slides

lecturenoteschap3-10-2slides - BCMB 3100 Chapter 3 (part 1)...

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1 BCMB 3100 – Chapter 3 ( part 1) Diversity of protein function • Complete definition of amino acids • Memorize complete structure of 20 common amino acids!!! •pK a s o f amino and carboxyl groups 1 • Amino acids with ionizable side groups • Titration curve PROTEIN STRUCTURE AND FUNCTION Mulder (1800s): showed albumins (milk and egg) contained Berzelius (1838): named such substances ________________ from Greek proteios "of first rank" Proteins recognize and many 2 different types of molecules & ___________ most of the ____________________ necessary for life.
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2 Examples of Protein Function ____________________: enzymes increase reaction rates by 6 10 -fold; nearly all known enzymes are proteins ____________________: many small molecules and ions are transported by proteins; examples: hemoglobin myoglobin 3 examples: hemoglobin, myoglobin ____________________: examples: myosin and actin (muscle movement) Examples of Protein Function ___________________: collagen (tensile strength to skin and bones) ___________________: antibodies __________________________________________ ____________: example: acetylcholine receptor 4 _________________________________: DNA binding proteins (repressors, activators, transcription factors, hormones, regulation of translation
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3 WHAT ARE PROTEINS? Proteins are macromolecules made up of amino acids (____________________) -amino acids : consist of an ____________ , a _______________ , a ________________ and a distinctive __________ bonded to a carbon atom. This carbon is called the _________ because it is adjacent to the carboxyl group. 5 BCMB 3100 - Chapter 3 •D iv e r s i ty of protein function Complete definition of amino acids • Memorize complete structure of 20 common amino acids!!! • pKa’s of amino and carboxyal groups 6 • Amino acids with ionizable side groups • Titration curves & pI
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4 Amino acids in solution will be in a charged state . The amino group and/or the carboxyl group will be charged depending upon the pH. The R group may also be charged. At neutral pH amino acids are predominantly __________________ (zwitterions ) • Under normal cellular conditions amino acids are zwitterions (dipolar ions) 7 acids are (dipolar ions): Amino group = -NH 3 + Carboxyl group = -COO - General Structure of the ionized from of an amino acid Fischer COO - NH 3 + C H R Projection 8 COO - : pKa 1.8-2.5 NH + : pKa 8.7-10.7 You MUST know this!!!
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5 Fig 3.1 Two representations of an amino acid at neutral pH (a) Structure (b) Ball-and stick model 9 (b) Ball and stick model Amino acids are ___________ (asymmetric) due to the tetrahedral array of 4 different groups around the -carbon (glycine is an exception). Thus all amino acids except glycine can exist as enantiomers: two sterioisomer that are nonsuperimposable mirror images of each other. Enantiomers of amino acids are called D (right-handed) or L (left-handed) 10 (right handed) or L (left handed) L and D refer to absolute configuration _________________ are the only constituents of proteins
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6 Fig 3.2 Mirror-image pairs of amino acids 11 20 different amino acids are found in proteins _____________________ (side chains) that differ in size, shape, charge, hydrogen- bonding capacity & chemical reactivity 20 different amino acids found in proteins of all organisms from bacteria to humans The amino acid alphabet is at least 2 billion years old The diversity of protein structure & function 12 is due to the sequence and number of amino
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This note was uploaded on 12/03/2011 for the course CHEM 3100 taught by Professor Dervartanian during the Fall '09 term at University of Georgia Athens.

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lecturenoteschap3-10-2slides - BCMB 3100 Chapter 3 (part 1)...

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