C(2)-Symmetric azobenzene-amino acid conjugates and their inhibition of Subtilisin Kexin Isozyme-1.

C(2)-Symmetric azobenzene-amino acid/peptide hybrids containing stable E-azo moiety have been synthesized. Upon irradiation with long wavelength UV, these compounds isomerized to the Z-form, whose thermal reisomerization to the E isomer slowed down considerably. These compounds exhibited in vitro moderate to strong inhibition of mammalian cellular protease Subtilisin Kexin Isozyme-1, also called Site 1 Protease, which plays vital roles in cholesterol synthesis, lipid metabolism, bone formation, and viral infections.

A novel enediynyl peptide inhibitor of furin that blocks processing of proPDGF-A, B and proVEGF-C.

BACKGROUND: Furin represents a crucial member of secretory mammalian subtilase, the Proprotein Convertase (PC) or Proprotein Convertase Subtilisin/Kexin (PCSK) superfamily. It has been linked to cancer, tumorgenesis, viral and bacterial pathogenesis. As a result it is considered a major target for intervention of these diseases. METHODOLOGY/PRINCIPAL FINDINGS: Herein, we report, for the first time, the synthesis and biological evaluation of a newly designed potent furin inhibitor that contains a highly reactive beta-turn inducing and radical generating "enediynyl amino acid" (Eda) moiety. "Eda" was inserted between P1 and P1' residues of hfurin(98-112) peptide, derived from the primary cleavage site of furin's own prodomain. The resulting hexadecapeptide derivative inhibited furin in vitro with IC(50) approximately 40 nM when measured against the fluorogenic substrate Boc-RVRR-MCA. It also inhibited furin-mediated cleavage of a fluorogenic peptide derived from hSARS-CoV spike protein with IC(50) approximately 193 nM. Additionally it also blocked furin-processing of growth factors proPDGF-A, B and VEGF-C that are linked to tumor genesis and cancer. Circular dichroism study showed that this inhibitor displayed a predominantly beta-turn structure while western blots confirmed its ability to protect furin protein from self degradation. CONCLUSION/SIGNIFICANCE: These findings imply its potential as a therapeutic agent for intervention of cancer and other furin-associated diseases.

Trans fatty acids: current contents in Canadian foods and estimated intake levels for the Canadian population.

Research conducted in the mid-1990s indicated that the levels of trans fats in Canadian diets were among the highest in the world. The consumption of trans fats raises blood levels of low-density lipoprotein (LDL)-cholesterol, while reducing levels of high-density lipoprotein (HDL)-cholesterol. In June 2007, Health Canada called on the food industry to voluntarily reduce levels of trans fats in vegetable oils and soft (tub)-margarines to < 2% of total fat, and in all other foods, to < 5%. Industry must show satisfactory progress by June 2009, or Health Canada might have to introduce legislation to ensure that recommended limits are achieved. Since 2005, Health Canada has been performing a national assessment of prepackaged and restaurant foods that likely contain trans fats. From 2005 to 2009, 1120 samples were analyzed, of which 852 or approximately 76% met the recommended trans fat limits. As a result of reformulation, most of the products had decreased trans + saturated fat content. The estimated average intake of trans fatty acids (TFA) in Canada significantly dropped from the high value of 8.4 g/day in the mid-1990s to 3.4 g/day (or 1.4% food energy) in 2008. However, this TFA intake of 1.4% of energy is still above the World Health Organization recommended limit of TFA intake of < 1% of energy, which suggests that the Canadian food industry needs to put more effort into reducing the TFA content in its products, especially in tub-margarines, donuts, and bakery products.

Multibranch and pseudopeptide approach for design of novel inhibitors of subtilisin kexin isozyme-1.

Here we developed small molecule inhibitors of SKI-1/S1P enzyme of the Proprotein Convertase family following two approaches. One involves the assembly of multi-branch peptides while the other utilizes the insertion of alkyloxy pseudo peptide bond at P1-P1' cleavage position. In first approach, 2 and 4-branch peptides were designed based on the human (h) SKI-1(128-137) sequence, located N-terminal to its secondary activation site (K(137) downward arrow L). The 4-branch peptide exhibited the highest SKI-1 inhibitory property (IC(50) = 0.9 microM) with approximately 8.6 and 1.3-fold more potency than the corresponding single and 2-branch peptides, respectively. In the second strategy, an oxymethylene containing unnatural amino acid such as aminooxy-acetic acid (Aoaa) or 8-amino-3, 6 dioxa-octanoic acid (Adoa) was introduced substituting P1, P1' or both residues of hSKI-1(183-190) and hSKI-1(178-190) segments. These domains contain the same primary hSKI-1 activation site L(186) downward arrow R. Among those tested, P7-Tyr mutant [(178)GRYSSRRL(Adoa)AIP(190)] exhibited higher SKI-1 inhibitory activity (K(i)in low microM). Circular dichroism (CD) spectra of SKI-1 inhibitors showed interactions of varying degrees between the enzyme and the inhibitor consistent with the observed inhibition profile. A 3D-homology model structure of SKI-1 catalytic domain indicated a broad catalytic pocket.