Potential Enzymes

Several other research teams used the Paal-Knorr condensation to prepare 2,5-disubstituted furans that were investigated as potential enzyme inhibitors. Nagai produced furan 17 via treatment of dione 16 with sulfuric acid and subsequently examined the activity of 17 toward a retenoic acid receptor. Perrier discovered that furan 19, derived from dione 18, is a potent PDE4 inhibitor and may have anti-inflammatory activity. ... 

Potential enzymes involved in anthocyanin metabolism — The lactase phlorizin hydrolase (LPH EC 3.2.1.108) present only in the small intestine on the outside of the brush border membrane and the cytosolic P-glucosidase (CBG EC 3.2.1.1) found in many tissues, particularly in liver, can catalyze the deglycosylation (or hydrolysis) of polyphenols. LPH may play a major role in polyphenol metabolism... 

It is worth mentioning here that the spirocyclopropyl-substituted oxazoline-5-car-boxylates 2-172, as well as the corresponding thiazoline-4-carboxylates, can be transformed into cyclopropyl-substituted amino acids, which might act as potential enzyme inhibitors [93] and interesting building blocks for peptidomimetics [94]. 

The Kemp elimination is of special interest because it is known to be extraordinarily sensitive to the medium, and particularly well suited as a test reaction for potential enzyme mimics because it is a simple, one-step process. The joint conclusions from this work were that catalysis involves a combination of a number of different factors, even for this simple reaction by these simple catalysts. 

What can be done if there is not an exact literature precedent for the required enzymatic transformation In these cases some sort of screening procedure may be necessary, either by direct screening of commercial enzymes, culture collections and environmental isolates, or by using a bioinformatics-based approach to identify potential enzymes based on sequence information. 

Scheme 2.45 Synthesis of potential enzyme farnesyl transferase inhibitors.

Scheme 2.2.S.7 Synthesis of sugar phosphonic acids as potential enzyme inhibitors.

Changes in the activity of enzymes may also occur by a variety of other parameters including temperature, pH, and ionic strength. Temperature can affect both the activity and the stability of the enzymes. For most enzymes, the reaction velocity doubles with a temperature increase of 10 C but potential enzyme denaturation may also occur (265). 

Metalloporphyrins have been used for epoxidation and hydroxylation [5.53] and a phosphine-rhodium complex for isomerization and hydrogenation [5.54]. Cytochrome P-450 model systems are represented by a porphyrin-bridged cyclophane [5.55a], macrobicyclic transition metal cyclidenes [5.55b] or /3-cyclodextrin-linked porphyrin complexes [5.55c] that may bind substrates and perform oxygenation reactions on them. A cyclodextrin connected to a coenzyme B12 unit forms a potential enzyme-coenzyme mimic [5.56]. Recognition directed, specific DNA cleavage... 

Field studies point in a similar direction field comparisons of peptide hydrolysis rates and amino acid turnover in coastal sediments showed that amino acid production could exceed uptake by a factor of approximately 8 (Pantoja and Lee, 1999). A comparison of potential enzyme activities and sedimentary amino acid and carbohydrate inventories in sediments from the Ross Sea also showed that potential hydrolysis rates on time scales of hours should in theory rapidly deplete sedimentary amino acid and carbohydrate inventories (Fabiano and Danovaro, 1998). In deep-sea sediments, Poremba (1995) also found that potential enzyme activities in theory could exceed total sedimentary carbon input by a factor of 200. Finally, Smith et al. s (1992) investigation of potential hydrolysis rates and amino acid uptake in marine snow demonstrated that the particle-associated bacteria were potentially producing amino acids far in excess of their own carbon demand. 

ARPM Valentijn, R de Hann, E de Kant, GA van der Marel, LH Cohen, JH van Boom. Synthesis of a potential enzyme-specific inhibitor of squalene synthase. Rec Trav Chim Pays-Bas 114 332-336, 1995. 

Once the role of a gene product as a potential enzyme target is identified via genetic techniques, such as cloning and complementation, the next step involves its biochemical characterization including the development of a quantitative... 

The food, feed, and paper industries use hemicellulase to convert hemicellulose to useful products (Wong and Saddler, 1993). At the concentrations found in vegetable waste matter, hemicellulose has been viewed intermit-tendy as a potential enzyme substrate and as feedstock for commercial ethanol and furfural production. 

Compound A was needed for conversion into the potential enzyme inhibitor below. How might this be achieved ... 

Aminocyclopropanecarboxylic acid (74) has attracted special interest (a) as a modified model of natural a-amino acids, in the synthesis of bioactive peptide analogs, potential enzyme inhibitors , or e.g. a derivative with sweetness receptor activity s and (b) together with its Schiff-base metal complexesas the biosynthetic precursor of ethene, the plant ripening hormone . (See these sources and the review in Reference 135 for further references.)... 

Both (IV) and (V) are stable in nonpolar solvents but not in acidic or basic solutions 127, 128). Similarly, the integrity of YCN is retained, but only in the structurally intact protein, in the absence of potential enzyme ligands (formic, acetic, or hydrofluoric acids). Such ligands promote a slow hydrolysis of YCN (Table VI) with a concomitant recovery of full enzymic activity 90). Furthermore, acid denaturation of the cyanylated enzyme at pH 2 is followed by complete hydrolysis of YCN (half-time 4 hr at pH 2, 25°) 90), and the formation of carbon dioxide, possibly via Eqs. (8) and (9) ... 

These four theozymes were then used as templates for fitting into 10 different protein scaffolds using the RosettaMatch algorithm. This search resulted in 72 potential enzymes, each with 8-20 residue changes from the parent scaffolds. These genes encoding these 72 enzymes were incorporated into E. coli and 70 of them led to successfully expressed protein. 

To get the potential enzyme inhibitor, we need to reduce the nitro group to an amine and add the new chain to the other amine. This conjugate addition must be done first while there is only one nucleophilic amine. The ester is probably the best acid derivative to use but you may have chosen another. 

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