Amino groups reagents

Anagnostopoulos found that the amino group reagents ketene, nitrous acid, formaldehyde, and phenyl isocyanate all inactivated bovine liver and kidney phosphatases 102). On the other hand, acetylation of chicken intestinal phosphatase with acetic anhydride gave an active product with optimum activity more alkaline than normal 103). The enzyme preparation was impure and acetylation only 70% complete... 

ATP is cleaved by most sarcoplasmic reticulum preparations at low rates in the absence of calcium ions. This activity has been denoted as basal activity [20]. When calcium accumulation is initiated, ATP is rapidly hydrolyzed in a calcium-dependent activity, reaching its optimum at a calcium concentration of 10 jaM, and which is severely suppressed by the rising calcium concentrations in the interior of the vesicles [45,64,65]. The calcium-dependent activity was early characterized as the activity of an enzyme distinctly different from the calcium-independent enzyme. In contrast to the calcium-dependent ATPase, the calcium-independent enzyme is quite insensitive to thiol or amino group reagents. Conversely, the calcium-independent activity can be abolished by low concentrations of detergents which do not reduce the activity of the calcium-dependent enzyme [66]. The two enzymatic activities further differ in their nucleotide specificity and affinity, as well as in their magnesium and temperature dependences. The basal activity most likely originates from plasmalemma and T-tubules membranes [41]. 

Yellow liquid m.p. 26" C, b.p. l37 "C/2mm. Reagent introduced by Sanger for identification of the terminal amino group of peptides with which it forms an /V-2,4-dlni-irophenyl derivative under mild conditions. 

Crystalline derivatives of amino acids are usually produced by reaction at the amino group by treatment with appropriate reagents in alkaline solution ... 

Mono-substitution products of primary amines cannot easUy be prepared by direct action of the appropriate reagent for example, bromination of aniline yields largely the 2 4 6-tribomo derivative and nitration results in much oxidation. If, however, the amino group is protected as in acetanilide, smooth substitution occurs. Thus with bromine, />-bromoacetanilide is the main product the small quantity of the ortlio isomeride simultaneously formed can be easily eliminated by crystallisation. Hydrolysis of p-bromoacetanilide gives/ -bromoaniline ... 

The keto tautomer (211a) is involved in the high electrophilic reactivin-of the C-5 carbonyl group. Thus ring opening has been reported u ith various amino nucleophilic reagents. 

The most used EIA reagents conjugate a fluotophote such as fluorescein-isothiocyanate (EITC) or thodarnine—isothiocyanate to antibody (or antigen) free amino groups. Examples of other commonly used fluotophotes for EIA and their spectral characteristics ate presented in Table 3. EIA assays ate available in sandwich and competitive formats similar to EIAs. Unlike EIA kits which can be used directly with visual color deterrnination, EIAs require a fluorometer, and thus ate primarily laboratory-based. 

Fig. 3. (a) Reaction of pytidoxal 5 -phosphate (PLP) witii an amino-temiinal amino group of hemoglobin (Hb). The reagent is in the form of a Schiff s base with tris(hydroxymethyl)aminomethane [77-86-1] (Tris) buffet, and the reaction is a transamination, (b) The resulting unstable Schiff s base is reduced with... 

Bis-Pyndoxal Tetraphosphate. A second class of bifunctional reagents, described in 1988, involves two pyridoxal groups linked by phosphates of different lengths (89). As shown in Table 4, the yield of intramolecularly cross-linked hemoglobin increases dramatically with increasing length of the phosphate backbone. It is beheved that the site of reaction of (bis-PL) is between the amino-terminal amino group of one P-chain and the... 

The kinetics of formation and hydrolysis of /-C H OCl have been investigated (262). The chemistry of alkyl hypochlorites, /-C H OCl in particular, has been extensively explored (247). /-Butyl hypochlorite reacts with a variety of olefins via a photoinduced radical chain process to give good yields of aUyflc chlorides (263). Steroid alcohols can be oxidized and chlorinated with /-C H OCl to give good yields of ketosteroids and chlorosteroids (264) (see Steroids). /-Butyl hypochlorite is a more satisfactory reagent than HOCl for /V-chlorination of amines (265). Sulfides are oxidized in excellent yields to sulfoxides without concomitant formation of sulfones (266). 2-Amino-1, 4-quinones are rapidly chlorinated at room temperature chlorination occurs specifically at the position adjacent to the amino group (267). Anhydropenicillin is converted almost quantitatively to its 6-methoxy derivative by /-C H OCl in methanol (268). Reaction of unsaturated hydroperoxides with /-C H OCl provides monocyclic and bicycHc chloroalkyl 1,2-dioxolanes. 

Canonical forms of type (442b) facilitate proton loss from the amino groups the anions formed react easily with electrophilic reagents, usually preferentially at the exocyclic nitrogen atom e.g. 443 -> 444) (79HC(34-2)9). 

The hydroxy and amino groups are highly activating ortho-para-d KCtmg groups. Such compounds are attacked by all the electrophilic reagents tabulated in Scheme... 

Benzoylate the amino groups by overspotting at [103] the start This makes detection with Gibbs reagent possible... 

Pentafluorophenyl acetate is a highly selective acetylating reagent, useful for acetylations at hydroxyl and amino groups under mild conditions When applied to the acetylation of amino alcohols, it gives selective formation of H acetyl derivatives at room temperature and M,0 diacetylated products under moderate heating in the presence of triethylamine [149]... 

Nitration of an aromatic ring does not occur in nature but is particularly important in the laboratory because the nitio-substituted product can be reduced by reagents such as iron, tin, or SnCl2 to yield an aryhmwie, ArNH2-Attachment of an amino group to an aromatic ring by the two-step... 

Here, bulky, and if R1 constitutes an oxy or amino group, nonchelating reagents, such as titanates or boronates, offer high substrate-induced stereoselectivities (Table 1). 

The addition of titanated allyl carbamates to jV-protectcd (S )-amino aldehydes allows rapid access to intermediates for various dipeptide isosteres98-10°, offering a versatile brick-box system (Table 5). If an acidic amino group is present, two equivalents of reagent are required. 

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