Structural features required for

The apparent necessity of a second signal for haustorial initiation provides another possibility for chemical control. Riopel and coworkers (2,12-14) observed a few years ago that gum tragacanth, a foliar extract, was a very potent haustorial initiator. Two active compounds were isolated (Xenognosin A shown below, and a flavonoid with similar structure). The structural features required for haustorial formation include a meta relationship of hydroxyl and methoxyl groups and an alkyl branching ortho to the methoxy substituent. 

Experiments using synthetic hydroxyurea derivatives provide information regarding the mechanism and the structural features required for NO release. O-Methyl-hydroxyurea (27, Fig. 7.5) fails to react with any type of hemoglobin [115]. N-... 

Maintaining DNA Structure (a) Describe two structural features required for a DNA molecule to maintain a negatively supercoiled state, (b) List three structural changes that become more favorable when a DNA molecule is negatively supercoiled. (c) What enzyme, with the aid of ATP, can generate negative superhelicity in DNA (d) Describe the physical mechanism by which this enzyme acts. 

Molecular modeling calculations using ab initio methods (MP2/6-31+G ) predict that spiro-(3-lactam of type M adopt a (3-tum secondary structure [50] which is very close to the ideal type-III (3-tums. Thus, these spiro-(3-lactams are the important members of the core for the preparation of different types of peptidomimetics using well-established chemistry. They combine the structural features required for inducing (3-tum motif. 

Despite the small size of glycolipids, their complexity has still driven efforts for synthesis of simpler mimetics in an attempt to identify the minimal structural features required for the biological activity. To this end, many synthetic methods have been adopted in glycolipids synthesis, based on traditional glycosylation... 

Bicyclo[2.2.2]oct-5,7-dien-2-ones 57a-c, which are endowed with the structural features required for both the ODPM and DPM rearrangements, undergo acetophenone-sensitized DPM rearrangement to afford the compounds 58a-c in good yields (Scheme 4.24) [34],... 

The simplest known sugar derivatives that interact with the jack-bean lectin are l,5-anhydro-2-deoxy-D-arahino-hexitol and 1,4-anhydro-D-arabinitol.168,215 These alditols contain the minimal structural features required for binding to con A, namely, unmodified hydroxyl groups of the B-arabino configuration at C-3, C-4, and C-5 of the... 

Enholm s strategy [26] involves incorporation of all the structural features required for the 6-heptenyl radical cychzation reaction into the monomer subunit prior to metathesis polymerization, thus ensuring maximum possible loading. Although several steps are needed to prepare the monomer unit and recycling the support is not possible, this work does show the potential of using chiral linking imits to control the stereochemistry of radical cycliza-tions on polymer supports. 

Recently, Michalak et al. [156] presented a review on the interactions of phenothiazines with lipid bilayers and their role in MDR reversal. The drug partition between water and the lipid phase was discussed. The molecular size and polarizability of phenothiazines were found to correlate satisfactorily with the reduction of MDR. The most important structural features required for a high anti-MDR activity of phenothiazines seem to be their hydrophobic ring system, the type of substituent located at the 2-position, the presence of... 

Structural Features Required for Optimal Protein Binding... 

Cheung AK, Murelli R, Snapper ML (2004) Total syntheses of (+)- and (—)-cacospongiono-lide B, cacospongionolide E, and related analogues. Preliminary study of structural features required for phospholipase A2 inhibition. J Org Chem 69 5712-5719... 

Fig. 19. Model of sialic acid structural features required for the interaction with sialate lyase and binding of inhibitors. Based on data from ref. [892].

A vast number of platinum compounds have now been screened for antitumor activity, and the results of these investigations have led to a set of empirical guidelines for the minimum structural features required for activity. Although they may be stated in various forms, the key structure-activity relationships... 

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