Amino acids drawing

Be able to solve acid-base problems involving amino acids, draw structures at various pH values, estimate isoelectric points and net charges, and construct and interpret their titration curves. 

TAMU scientists synthesized a similar tetrapeptide, with the synthetic amino acid above replacing one of the original amino acids. Draw a structure for the tetrapeptide containing the synthetic amino acid. 

What is the major difference between proline and the other amino acids Draw the structure of a dipeptide in which the amino group of proline forms a peptide bond with the carboxyl group of alanine. 

Using the four symbols shown to represent four different amino acids, draw structures four possible peptides for a four-member chain that can be made by linking them together in different orders. 

What is an amino acid Draw and label a generalized structure for an amino acid. 

What are amino acids Draw a general structure for amino acids. 

Although most naturally occurring proteins are made up only of L amino acids, proteins isolated from bacteria will sometimes contain d amino acids. Draw Fischer projections for D-alanine and D-valine. In each case, assign the configuration (R or S) of the chirality center. 

For each of the following amino acids, draw the form that is expected to predominate at physiological pH ... 

For each amino acid, draw the structure that predominates at the isoelectric point ... 

Alanine is a naturally occurring amino acid. Draw its structure using a perspective formula. 

Fig. 1. Schematic drawing of precursors for selected brain oligopeptides. Shaded areas represent the location of sequences of active peptide products which are normally cleaved by trypsin-like enzymes acting on double-basic amino acid residues. Precursors are not necessarily drawn to scale, (a) CRF precursor (b) proopiomelanocortin (POMC) (c) P-protachykinin (d) proenkephalin A (e) CGRP precursor (f) preprodynorphin, ie, preproenkephalin B. Terms are...

Consider, for example, the protein shown in Figure 15.7. The bottom left-hand amino acid is valine, which is linked to proline. Suppose for the sake of argument that we wanted to treat this valine quantum-mechanically and the rest of the protein chain according to the methods of molecular mechanics. We would have to draw a QM/MM boundary somewhere between valine and the rest of the protein. The link atoms define the boundary between the QM and the MM regions. A great deal of care has to go into this choice of boundary. The boundary should not give two species whose chemical properties are quite different from those implied by the structural formulae on either side of this boundary. 

Problem 9.3. Alanine, an amino acid found in proteins, is chiral. Draw the two enantiomers of ala- nine using the standard convention of solid, wedged, and dashed lines. 

Draw tetrahedral representations of the two enantiomers of the amino acid cysteine, HSCfi CHfNH lCX H, and identify each as R or S. 

Except for cysteine, only S amino acids occur in proteins. Several R amino acids are also found in nature, however. (ft)-Serine is found in earthworms, and (R)-alanine is found in insect larvae. Draw Fischer projections of (fl)-serine and (J )-alanine. Are these Don amino acids ... 

Draw resonance forms for the purple anion obtained by reaction of ninhydrin with an n-amino acid (Problem 26.53). 

Draw the complete structure of the ribonucleotide codon UAC. For what amino acid does this sequence code ... 

The structure of all TK receptors is similar in terms of expression oiTACR genes, since all these genes contain five exons intercalated by four introns [1, 5]. Exon I encodes for the N-terminal extracellular tail, the first intracellular (IC1) and extracellular (EC1) loops and the first, second, and third transmembrane domains (TM1, TM2, and TM3). Exon II encodes for the second intracellular (IC2) and extracellular (EC2) loops and the fourth transmembrane domain (TM4). Exon III encodes for the fifth transmembrane domain (TM5) and the third intracellular loop (IC3). Exon IV encodes for the sixth and seventh transmembrane domains (TM6 and TM7) and the third extracellular loop. Exon V encodes for the C-terminal intracellular tail only. A schematic drawing of the amino acid sequences and TK receptor organization is shown in Fig. 1. 

A segment of a protein is analyzed and found to contain the amino acid sequence Glu-Lcu-Asp. Draw the Lewis structure of this segment, showing the peptide bonds. 

C13-0002. Amino acids are the molecular building blocks of proteins. Any two amino acids can condense in two ways each creates an amide linkage. Draw the stmetures of the two condensation products that link these two amino acids ... 

The primary structure of a polypeptide is its sequence of amino acids. It is customary to write primary structures of polypeptides using the three-letter abbreviation for each amino acid. By convention, the structure is written so that the amino acid on the left bears the terminal amino group of the polypeptide and the amino acid on the right bears the terminal carboxyl group. Figure 13-35 shows the two dipeptides that can be made from glycine and serine. Although they contain the same amino acids, they are different molecules whose chemical and physical properties differ. Example shows how to draw the primary stmcture of a peptide. 

C18-0142. The amine group of an amino acid readily accepts a proton, and the protonated form of an amino acid can be viewed as a diprotic acid. The p Zg values for serine (H2 NCHRCO2 H, i = CH2 OH) are p ra(H3 N"") =9.1 and p (002 H) - 2.2. (a) What is the chemical formula of the species that forms when serine dissolves in pure water (b) If this species is titrated with strong acid, what reaction occurs (c) 10.00 mL of 1.00 M HCl is added to 200. mL of 0.0500 M serine solution. This mixture is then titrated with 0.500 M NaOH. Draw the titration curve, indicating the pH at various stages of this titration. 

---