Terminal amine

Initially, the water slowly reacts with the isocyanate. However, the reaction can be catalyzed with an appropriate catalyst, such as dibutyltin dilaurate or a morpholine tertiary amine catalyst. The isocyanate will react with water to form a carbamic acid, which is unstable and splits off carbon dioxide, to produce a terminal amine end group (see p. 76 in [6]). This amine then reacts with more isocyanate-terminated prepolymer, as shown above, to form a polyurea. This process repeats itself, building up molecular weight and curing to become a polyurea-polyurethane adhesive. 

Closely related is the reaction of enamines with O-sulfonyl lactams (411-413), which has extended the versatility of Hiinig s carboxylic acid extension sequence to compounds with a terminal amine function. 

Various phenallcylamines were shown to produce either DOM-like or AMPH-like stimulus effects the structure-activity requirements for these activities are different from the standpoints of aromatic substitution patterns, terminal amine substituents, and optical activity. Thus, it has been possible to formulate two distinct SARs. It should be realized, however, that phenalkylamines need not produce only one of these two types of effects certain phenallcylamines can produce pharmacological effects like neither DOM nor AMPH. Moreover, they can produce effects that are primarily peripheral, not central, in nature (Glennon 1987a). The fact that an agent produced DOM- or AMPH-like effects does not imply that it carmot produce an additional effect conversely, if an agent does not produce either DOM- or AMPH-like stimulus effects, it is not necessarily inactive. 

Another interesting target for this type of inhibitors is the dipeptidyl peptidase IV (DPP IV). This exodipeptidase, which can cleave peptides behind a proline residue is important in type 2 diabetes as it truncates the glucagon-like peptide 1. Taking into account the P2-Pi( Pro)-P,1 cleavage and the requirement for a free terminal amine, the synthesis of a suicide inhibitor was planned. It looked as if the the e-amino group of a P2 lysine residue could be cyclized because of the relative little importance of the nature of the P2 residue on the rate of enzymatic hydrolysis of known synthetic substrates. Therefore, anew series of cyclopeptides 11 was synthesized (Fig. 11.8). 

Finally, we have studied the reaction of amino-terminated polyoxyethylenes with the poly(vinylbenzyl chloride) latex (18). The rate of this reaction was found to be independent of the length of the chain carrying the terminal amine. Attachment of these chains stabilized the latex against coagulation, in analogy with the "steric stabilization" produced by adsorbed polymer chains (19 ). ... 

The insertion of histidine in position two of the peptide chain results in the simultaneous binding of the N-terminal amine, the imidazole, and the intervening amide-N to the Ni11 ion. The major complex [NiH iL]+ with NH2,N am,Nim binding mode is pseudo-octahedral and in... 

Carbon dioxide can combine chemically with the terminal amine groups (NH2) in blood proteins. The most important of these proteins for this process is hemoglobin. The combination of carbon dioxide and hemoglobin forms carbamino hemoglobin ... 

Fig. 4 PEGylation at the N-terminal methionine residue. The difference in pKa. between the N-terminal amine and other amines in the protein enables site-specific PEGylation. After reaction with aldehyde-terminated PEG at low pH, reduction of the resultant imine produces PEGylated protein...

Aldehyde groups can be converted into terminal amines by a reductive amination process with ammonia or a diamine compound. The reaction proceeds by initial formation of a Schiff base... 

Isothiocyanates react with nucleophiles such as amines, sulfhydryls, and the phenolate ion of tyrosine side chains (Podhradsky et al., 1979). The only stable product, however, is with primary amine groups, and so TRITC is almost entirely selective for modifying s- and N-terminal amines in proteins. The reaction involves attack of the nucleophile on the central, electrophilic... 

The crosslinking scheme using this method can make use of the native e- and N-terminal amines on carrier proteins as the source of primary amine for the condensation reaction. Added to the conjugation reaction then is formaldehyde and the desired hapten to be coupled containing an appropriately active hydrogen. 

Tryptamines that are unsubstituted on the terminal amine are good substrates for oxidative deamination by MAO. Furthermore, it has been demonstrated that tryptamine and 5-methoxytryptamine cross the blood-brain barrier with great difficulty administration of 50 mg/kg 5-methoxytryptamine to rats results in a low brain/plasma ratio when measured 15 min postadministration (242). 

---