Maleimide derivatives

Condensation of o-aminoacetophenone with maleic, succinic or phthalic anhydrides gave 117 whose bromination with CuBr2 gave the bromides 118. Column chromatographic separation of the respective maleimide derivative on silica gel gave the bromoquinoline 119 whereas the phthalimide derivative was obtained from 118 by cyclization with EtsN (93MI11). On the... 

More elaborate maleate and maleimide derivatives have provided a route to grafting various functionalities onto PP. Examples, include antioxidants (29 and 30) 1 11 and the oxazolinc derivative (31 )H2J33 for which very high grafting yields were reported. 

A method for reaction conditions. Monomers that have been used include MAH and maleimide derivatives such as NPMI (Scheme 9.51).582 In these cases, elimination of hydroxylamine under the reaction conditions provides an unsaturated end group. 

Reaction of purified Ca " -ATPase with 0.3 mM NBD-Cl in the presence of 1 mM AMP-PNP and 1 mM CaCl2 caused inhibition of ATPase activity with the incorporation of 2= 15 nmol NBD-Cl per mg protein [335]. The inhibition was attributed to the binding of 7-8 nmol NBD-Cl/mg enzyme protein, corresponding to = 1 mol NBD-Cl per mol ATPase. The NBD-labeled enzyme was digested with pepsin and several NBD-labeled peptides were isolated [335]. All peptides contained the Gly-X (Cys) sequence that occurs only in one place in the Ca -ATPase, i.e., at Gly343-Cys344. Therefore NBD-Cl reacts with the same cysteine 344 residue that is also modified by maleimide derivatives [319]. The NBD modified enzyme had only 5-10% of the ATPase activity of the control ATPase, but the steady state concentration of the phosphoenzyme intermediate was only slightly reduced [335]. The Ca ... 

The reaction of diaryl compounds 2-974 with 3 equiv. of DB U at r. t. results initially in an intramolecular aldol condensation to give 2-975 this is followed by an oxidation to give the 3,4-diaryl disubstituted maleic anhydride or maleimide derivatives 2-976 when the reaction is conducted under atmospheric oxygen (Scheme 2.219). 

The Diels-Alder adduct, anhydride 63, on treatment with hydrazine hydrate in acetic acid for 20 min yielded 252 which on keeping in acetic acid for further 8 h gave the imide derivative 253. This adduct, imide 253, underwent retro-Diels-Alder reaction to eliminate furan giving amino maleimide derivative 254 (Scheme 45) <2005J OC4553>. 

The reaction kinetics between a maleimide derivative and a 3,5-hexadiene derivative varies depending on the maleimide compound being reacted. Cycloaddition yields of greater than 80 percent and often as much as 90-95 percent can be expected within 1-18 hours at room temperature or slightly elevated reaction conditions (e.g., 30°C). 

Figure 19.16 A common way of conjugating sulfhydryl-containing haptens to carrier proteins is to activate the carrier with sulfo-SMCC to create an intermediate maleimide derivative. The maleimide groups then can be coupled to thiols to form thioether bonds.

Figure 19.18 Carrier proteins may be activated with sulfo-SMCC to produce maleimide derivatives reactive with sulfhydryl-containing molecules. The graphs show the gel filtration separation on Sephadex G-25 of male-imide-activated BSA (A) and OVA (B) after reaction with sulfo-SMCC. The first peak is the protein and the second peak is excess crosslinker. The maleimide groups create increased absorbance at 280 nm in the activated proteins.

The correct ratio of lipid constituents is important to form stable liposomes. For instance, a reliable liposomal composition for encapsulating aqueous substances may contain molar ratios of lecithin cholesterol negatively charged phospholipid (e.g., phosphatidyl glycerol (PG)) of 0.9 1 0.1. A composition that is typical when an activated phosphatidylethanolamine (PE) derivative is included may contain molar ratios of phosphatidylcholine (PC) cholesterol PG derivatized PE of 8 10 1 1. Another typical composition using a maleimide derivative of PE without PG is PC male-imide-PE cholesterol of 85 15 50 (Friede et al., 1993). In general, to maintain membrane stability, the PE derivative should not exceed a concentration ratio of about l-10mol PE per lOOmol of total lipid. 

Figure 22.12 The reaction of SPDP with PE creates a maleimide derivative capable of coupling thiols. Reaction with a sulfhydryl-containing molecule forms a conjugate through a thioether linkage.

Figure 22.13 MBS reacted with PE produces a maleimide derivative that can couple to thiol compounds through a stable thioether bond.

In addition to UCN-01 and other staurosporine or maleimide derivatives (e.g., compounds 17 and 18 Fig. 4) [102,103,105-107], PDKl kinase activity is inhibited by aminopyrimidines. A representative example of this compound class is BX-320 (compound 19, Fig. 4), a PDKl inhibitor (IC50 = 30 nM) that displays good selectivity over protein kinase A (PKA, 35-fold) [108]. BX-320 blocks the growth in soft agar of a wide range of tumor cell lines (IC50 = 0.093 to 1.32 xM), and shows efficacy in a metastasis mouse model (200 mg/kg bid). 

Labelling Chemistry and Sequencing. The two main groups for labelling proteins are amine reactive and thiol reactive. For reaction with the amino groups in proteins the fluorophore is converted into the succinimidyl ester derivative by reaction with iV-hydroxysuccinimide, e.g. (3.74), and for reaction with thiols group this is achieved by making iodoacetamide or maleimide derivatives, e.g. (3.75). 

Medina et al. (1) photodimerized maleimide derivatives, (I), as a method for preparing semitelechelic silicone hydrogel polymers useful as for lens coatings as illustrated in Eq. (1). 

This procedure is carried out immediately before reacting thiolated avidin with the maleimide derivative of the antibody or enzyme prepared in Section 3.1.2. 

It is essential that the procedure described in Section 3.1.2. be performed approx 24 h before the procedure described in Section 3.1 3, because the deprotected thiolated avidin and the maleimide derivative of the protein are unstable. Purification of the maleimide-derivatized protein by size exclusion chromatography can be performed more rapidly than dialysis, however, the former leads to dilution of the protein and a decrease in the yield of the conjugate. 

Prepare the antibody for reduction. For labeling IgG antibodies with thiol-reactive reagents, the antibody should be at 5-10 mg of pro-tein/mL in 20 mM sodium or potassium phosphate buffer, pH 7.5-8.0 containing 150 mill NaCl or 10 mM phosphate-buffered saline ethylene diamine tetraacetic acid (PBS-EDTA). When biotin maleimide or biocytin maleimide derivatives are used, the buffer used for the reduction and subsequent steps should be at pH 6.5-7.2. 

Wamhoff and Hupe [78] have irradiated 3,4-dibromo-A-methylmaleimide in benzene in the presence and in the absence of a sensitizer (X < or >313 nm). A mixture of products was formed in which two compounds were detected that had the skeleton of the primary ortho adduct. One of these products had been formed from the primary adduct by the addition of bromine at one of the double bonds of the diene moiety. The second compound had undergone further bromination at the allylic position in the six-membered ring. The photodimer of 3,4-dibromo-A-methylmaleimide, which was also formed, was considered to be the source of the bromine. This is one of the rare instances in which the primary 1 1 adduct of benzene and a maleimide derivative could be isolated, albeit in brominated form. 

All of the above dyes can be purchased in N-succinimide activated form and used for labeling of amino groups (see below). The choice of fluor-ophores are more limited for labeling of thiol groups with maleimide derivatives of dyes, and especially for full synthesis of oligos using dye-labeled phosphoramidites. 

M14. Monji, N., Malkus, H., and Castro, A., Maleimide derivative of hapten for coupling to enzyme A new method in enzyme immunoassay. Biochem. Biophys. Res. Commun. 85, 671-677 (1978). 

Fig. 1. Unreactive maleimide derivatives in the PIFA-mediated oxidative cyclization reaction.

Nitrosation of pyrrole or alkylpyrroles can result in ring opening or oxidation of the ring and removal of the alkyl groups. This is illustrated by the formation of the maleimide derivative 147 from 2,3,4-trimethylpyrrole. 

Thermolysis of indole maleimide derivative 263 led to deprotection and cyclization to form substituted azonine system 264, as a sole product, in 45% yield (Equation 31) <2005JOC2206>. 

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