Expedited Solid-Phase Synthesis of Fluorescently Labeled and Biotinylated Aminoalkane Diphenyl Phosphonate Affinity Probes for Chymotrypsin- and Elastase-Like Serine Proteases

In this study, we report on a novel, expedited solid-phase approach for the synthesis of biotinylated and fluorescently tagged irreversible affinity based probes for the chymotrypsin and elastase-like serine proteases. The novel solid-phase biotinylation or fluorescent labeling of the aminoalkane diphenyl phosphonate warhead using commercially available Biotin-PEG-NovaTag or EDANS NovaTag resin permits rapid, facile synthesis of these reagents. We demonstrate the kinetic evaluation and utilization of a number of these irreversible inactivators for chymotrypsin-like (chymotrypsin/human cathepsin G) and elastase-like serine proteases. Encouragingly, these compounds display comparable potency against their target proteases as their N-benzyloxycarbonyl (Cbz)-protected parent compounds, from which they were derived, and function as efficient active site-directed inactivators of their target proteases. We subsequently applied the biotinylated reagents for the sensitive detection of protease species via Western blot, showing that the inactivation of the protease was specifically mediated through the active site serine. Furthermore, we also demonstrate the successful detection of serine protease species with the fluorescently labeled derivatives “in-gel”, thus avoiding the need for downstream Western blotting. Finally, we also show the utility of biotinylated and pegylated affinity probes for the isolation/enrichment of serine protease species, via capture with immobilized streptavidin, and their subsequent identification via de novo sequencing. Given their selectivity of action against the serine proteases, we believe that these reagents can be exploited for the direct, rapid, and selective identification of these enzymes from biological milieu containing multiple protease subclasses.

On the Study of Network Coded AF Transmission Protocol for Wireless Multiple Access Channels

In this paper, the performance of the network coded amplify-forward cooperative protocol is studied. The use of network coding can suppress the bandwidth resource consumed by relay transmission, and hence increase the spectral efficiency of cooperative diversity. A distributed strategy of relay selection is applied to the cooperative scheme, which can reduce system overhead and also facilitate the development of the explicit expressions of information metrics, such as outage probability and ergodic capacity. Both analytical and numerical results demonstrate that the proposed protocol can achieve large ergodic capacity and full diversity gain simultaneously.

Generic Ergodic Capacity Bounds for Fixed-Gain AF Dual-Hop Relaying Systems

This paper elaborates on the ergodic capacity of fixed-gain amplify-and-forward (AF) dual-hop systems, which have recently attracted considerable research and industry interest. In particular, two novel capacity bounds that allow for fast and efficient computation and apply for nonidentically distributed hops are derived. More importantly, they are generic since they apply to a wide range of popular fading channel models. Specifically, the proposed upper bound applies to Nakagami-m, Weibull, and generalized-K fading channels, whereas the proposed lower bound is more general and applies to Rician fading channels. Moreover, it is explicitly demonstrated that the proposed lower and upper bounds become asymptotically exact in the high signal-to-noise ratio (SNR) regime. Based on our analytical expressions and numerical results, we gain valuable insights into the impact of model parameters on the capacity of fixed-gain AF dual-hop relaying systems. © 2011 IEEE.