1. Synthesis and biological activity of potent, low molecular weight renin inhibitors
J Sueiras-Diaz, D M Jones, M Szelke, J Deinum, L Svensson, C Westerlund, M Sohtell J Pept Res. 1997 Oct;50(4):248-61. doi: 10.1111/j.1399-3011.1997.tb01466.x.
A series of renin inhibitors containing the dipeptide transition state mimics (2R,4S,5S)-5-amino-4-hydroxy-2-methyl-6-cyclohexyl hexanoic acid (Cha-psi[CH(OH)CH2]Ala) and (2R,4S,5S)-5-amino-4-hydroxy-2-isopropyl-6-cyclohexyl hexanoic acid (Cha-psi[CH(OH)CH2]Val) were prepared. A structure-activity study, using pseudopeptide (Boc-Phe-His-Leu-psi[CH(OH)CH2]Val-Ile-His-OH) as our lead structure, led to a new series of inhibitors, which correspond to tripeptides and contain no natural amino acids. For example, R,S-Bpma-Ape-Cha-psi[CH(OH)CH2]Ala-NH2 (IC50 = 1.26 nM against human plasma renin at pH 6.0; molecular weight = 564) has only two thirds of the molecular weight but twice the potency of our original lead. This new class of low molecular weight renin inhibitor displays excellent specificity toward human renin versus the related aspartic proteinase pepsin and angiotensin-1-converting enzyme. Examples are given of selected inhibitors showing encouraging evidence for intestinal absorption after intracolonic and oral administration in male Sprague-Dawley rats.
2. Hydroxyethylamine isostere of an HIV-1 protease inhibitor prefers its amine to the hydroxy group in binding to catalytic aspartates. A synchrotron study of HIV-1 protease in complex with a peptidomimetic inhibitor
Jan Dohnálek, Jindrich Hasek, Jarmila Dusková, Hana Petroková, Martin Hradilek, Milan Soucek, Jan Konvalinka, Jirí Brynda, Juraj Sedlácek, Milan Fábry J Med Chem. 2002 Mar 28;45(7):1432-8. doi: 10.1021/jm010979e.
A complex structure of HIV-1 protease with a hydroxyethylamine-containing inhibitor Boc-Phe-Psi[(S)-CH(OH)CH2NH]-Phe-Gln-Phe-NH2 has been determined by X-ray diffraction to 1.8 A resolution. The inhibitor is bound in the active site of the protease dimer with its hydroxyethylamine isostere participating in hydrogen bonds to the catalytic aspartates 25 and 25' and glycine 27' of the active site triads via five hydrogen bonds. The isostere amine interactions with the catalytic aspartates result in a displacement of the isostere hydroxy group in comparison with the common position known for analogous hydroxyethylamine containing inhibitors. A comparison with another inhibitor of this series shows that the change of one atom of the P2' side chain (Glu/Gln) leads to an altered ability of creating hydrogen bonds to the active site and within the inhibitor molecule. The diffraction data collected at a synchrotron radiation source enabled a detailed analysis of the complex solvation and of alternative conformations of protein side chains.
3. Highly efficient synthesis of endomorphin-2 under thermodynamic control catalyzed by organic solvent stable proteases with in situ product removal
Jiaxing Xu, Honglin Sun, Xuejun He, Zhongzhong Bai, Bingfang He Bioresour Technol. 2013 Feb;129:663-6. doi: 10.1016/j.biortech.2012.12.036. Epub 2012 Dec 19.
An efficient enzymatic synthesis of endomorphin-2 (EM-2) was achieved using organic solvent stable proteases in nonaqeous media, based on thermodynamic control and an in situ product removal methodology. The high stability of biocatalysts in organic solvents enabled the aleatoric modulation of the nonaqueous reaction media to shift thermodynamic equilibrium toward synthesis. Peptide Boc-Phe-Phe-NH2 was synthesized with a high yield of 96% by the solvent stable protease WQ9-2 in monophase medium with an economical molar ratio of the substrate of 1:1. The tetrapeptide Boc-Tyr-Pro-Phe-Phe-NH2 was synthesized with a yield of 88% by another organic solvent tolerant protease PT121 from Boc-Tyr-Pro-OH and Phe-Phe-NH2 in an organic-aqueous biphasic system. The reaction-separation coupling in both enzymatic processes provides "driving forces" for the synthetic reactions and gives a high yield and high productivity without purification of the intermediate, thereby making the synthesis more amenable to scale-up.
