Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human immunodeficiency virus type-1 (HIV-1) reverse transcriptase (RT) plays a central role in the virus replication cycle. We found that HIV-1 RT was rapidly degraded when incubated with cell extracts obtained from human peripheral blood cells. The proteolytic activity responsible for the in vitro degradation of RT was present in monocytes and their precursors. Interestingly, this activity was downregulated upon cell activation or differentiation along the macrophage pathway. The proteolytic process appears specific for HIV-1 RT since other HIV-1 proteins were not degraded upon incubation in the same extracts. Although the degradation of RT was unaffected by specific proteasome inhibitors, it could be inhibited by PMSF and aprotinin, suggesting the involvement of a serine protease. Upon cell fractionation, this serine protease was found to be associated with the microsomal fraction and displayed an apparent molecular weight of approximately 2000 kDa, as determined by gel filtration. Our results suggest that a giant serine protease, different from tripeptidyl peptidase II, is involved in the in vitro degradation of HIV-1 RT. The possibility of an in vivo interaction between HIV-1 RT and a cell-type-specific serine protease is discussed.
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PMID:Human monocytes possess a serine protease activity capable of degrading HIV-1 reverse transcriptase in vitro. 1146 30

A novel approach to improve the antiviral efficacy of nucleoside reverse transcriptase inhibitors (NRTIs) and reduce their side effects was developed by constructing a nanosized NRTI monophosphate-polymer conjugate using d4T as a model NRTI. Firstly, a novel chitosan-O-isopropyl-5'-O-d4T monophosphate conjugate with a phosphoramidate linkage was efficiently synthesized through Atherton-Todd reaction under mild conditions. The anti-HIV activity and cytotoxicity of the polymeric conjugate were evaluated in MT4 cell line. Then the conjugate nanoparticles were prepared by the process of ionotropic gelation between TPP and chitosan-d4T conjugate to improve their delivery to viral reservoirs, and their physicochemical properties were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) techniques and X-ray diffraction (XRD). In vitro drug release studies in pH 1.1 and pH 7.4 suggested that both chitosan-d4T conjugate and its nanoparticles prefer to release d4T 5'-(O-isopropyl) monophosphate than free d4T for prolonged periods, which resulted in the enhancement of anti-HIV selectivity of the polymeric conjugate relative to free d4T due to bypassing the metabolic bottleneck of monophosphorylation. Additionally, the crosslinked conjugate nanoparticles can prevent the coupled drug from leaking out of the nanoparticles before entering the target viral reservoirs and provide a mild sustained release of d4T 5'-(O-isopropyl) monophosphate without the burst release. The results suggested that this kind of chitosan-O-isopropyl-5'-O-d4T monophosphate conjugate nano-prodrugs may be used as a targeting and sustained polymeric prodrugs for improving therapy efficacy and reducing side effects in antiretroviral treatment.
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PMID:Synthesis, nanosizing and in vitro drug release of a novel anti-HIV polymeric prodrug: chitosan-O-isopropyl-5'-O-d4T monophosphate conjugate. 1995 68