Amide link

Almost all actinomycins have the same chromophore, a planar phenoxa2inone dicarboxyUc acid called actinocin. In dactinomycin, the stmcture of which is shown in Figure 12, the two pendent pentapeptide lactones are identical, but in other actinomycins these lactones may be different. In other actinomycins the first amino acid, amide linked with actinocin, is usually L-threonine, as in dactinomycin the second position is sometimes D-aHo-isoleucine instead of D-valine the third position may be sarcosine or oxoproline the fourth position is sarcosine and the fifth position is sometimes /V-methyl isoleucine instead of /V-methylvaline. The lactone ring is always present. 

Chapter 5 Compounds which contain either an ester or an amide link in a single macrocyclic ring. This includes lactones, lactams, carbonates, carbamates, ureas, phosphates, etc. including sulfur, nitrogen and other atoms in the ring. 

Four different types of lipid-anchoring motifs have been found to date. These are amide-linked myristoyl anchors, thioester-linked fatty acyl anchors, thioether-linked prenyl anchors, and amide-linked glycosyl phosphatidylinosi-tol anchors. Each of these anchoring motifs is used by a variety of membrane proteins, but each nonetheless exhibits a characteristic pattern of structural requirements. 

Nonionic template synthesis of amide-linked catenanes and rotaxanes with macroheterocyclic fragments 97AG(E)930. 

In Section 18-6.3 the composition of proteins was given. They are large, amide-linked polymers of amino acids. However, the long chain formula (Figure 18-14, p. 348) does not represent all that is known about the structure of proteins. It shows the covalent structure properly but does not indicate the relative positions of the atoms in space. 

Myristoylation is the post-translational addition of the 14-carbon fatty acid myristate to the N-terminal glycine of proteins via an amide link. Myristoylation of proteins helps to anchor them to membranes. 

In condensation polymers, the monomers are linked together by condensation reactions, like those used to form ester or amide links. Polymers formed by linking together monomers that have carboxylic acid groups with those that have alcohol groups are called polyesters. Polymers of this type are widely used to make artificial fibers. A typical polyester is Dacron, or Terylene, a polymer produced from the... 

SOLUTION (a) Amide groups are present in the backbone, and so the polymer is a polyamide. Because the amide groups face in opposite directions, there are two different monomers, one with two acid groups and the other with two amine groups. We split each amide group apart and add a molecule of water to each amide link. 

Figure 17-5. Oxidative decarboxylation of pyruvate by the pyruvate dehydrogenase complex. Lipoic acid is joined by an amide link to a lysine residue of the transacetylase component of the enzyme complex. It forms a long flexible arm, allowing the lipoic acid prosthetic group to rotate sequentially between the active sites of each of the enzymes of the complex. (NAD nicotinamide adenine dinucleotide FAD, flavin adenine dinucleotide TDP, thiamin diphosphate.)...

SCHEME 54. Amide-linked mannosylated PAMAM dendrimers.404... 

Figure 4.9 EGS reacts with amine-containing molecules to form amide linked conjugates. The ester groups within its cross-bridge are cleavable under alkaline conditions using hydroxylamine.

E.R. Evitt, Catalytica Associates, Inc In their work with amide-linked cofacial porphyrins, Collman and Anson have only observed 100% four-electron O2 reduction in the four-atom-bridged member of the series. Your comments implied four-electron O2 reduction is observed with the five and eight as well as four-atom bridged methylene-linked cofacial porphyrins you have prepared. Is such activity observed for the compounds with longer linkages ... 

Bialek K, Cohen JD. Isolation and partial characterization of the major amide-linked conjugate of indole-3-acetic acid from Phaseolus vulgaris. Plant Physiol 1986 80 99-104. 

R. Jager, F. Vogtle, A New Synthetic Strategy towards Molecules with Mechanical Bonds Nonionic Template Synthesis of Amide-Linked Catenanes and Rotaxanes , Angew. Chem Int. Ed. Engl. 1997,36,930-944. 

Enzyme-catalyzed transfer of KDO from CMP-KDO (127) into a lipid-A acceptor has been studied by Heath and coworkers,1 using a cell-free system from Escherichia coli O 111 J-5. LPS from the organism did not function as an acceptor, and only weak acceptor-activity was displayed147-148 by lipid A preparations obtained by mild, acid-catalyzed hydrolysis of LPS. Base-catalyzed, hydrolytic removal of the ester-linked, but not the amide-linked, fatty acid residues from lipid A resulted in an acceptor of maximal activity1 (see Scheme 38 compare Scheme 39). 

---