Search

Proteases are among the largest protein families and critical regulators of biochemical processes like apoptosis and blood coagulation. Knowledge of proteases has been expanded by the development of proteomic approaches, however, technology for multiplexed screening of proteases within native environments is currently lacking behind. Here we introduce a simple method to profile protease activity based on isolation of protease products from native lysates using a 96FASP filter, their analysis in a mass spectrometer and a custom data analysis pipeline. The method is significantly faster, cheaper, technically less demanding, easy to multiplex and produces accurate protease fingerprints. Using the blood cascade proteases as a case study, we obtain protease substrate profiles that can be used to map specificity, cleavage entropy and allosteric effects and to design protease probes. The data further show that protease substrate predictions enable the selection of potential physiological substrates for targeted validation in biochemical assays.

Tick Anticoagulant Peptide (TAP), a 60-amino acid protein from the soft tick Ornithodoros moubata, inhibits activated coagulation factor X (fXa) with almost absolute specificity. Despite TAP and Bovine Pancreatic Trypsin Inhibitor (BPTI) (i.e., the prototype of the Kunitz-type protease inhibitors) sharing a similar 3D fold and disulphide bond topology, they have remarkably different amino acid sequence (only ~24% sequence identity), thermal stability, folding pathways, protease specificity, and even mechanism of protease inhibition. Here, fully active and correctly folded TAP was produced in reasonably high yields (~20%) by solid-phase peptide chemical synthesis and thoroughly characterised with respect to its chemical identity, disulphide pairing, folding kinetics, conformational dynamics, and fXa inhibition. The versatility of the chemical synthesis was exploited to perform structure–activity relationship studies on TAP by incorporating non-coded amino acids at positions 1 and 3 of the inhibitor. Using Hydrogen–Deuterium Exchange Mass Spectrometry, we found that TAP has a remarkably higher conformational flexibility compared to BPTI, and propose that these different dynamics could impact the different folding pathway and inhibition mechanisms of TAP and BPTI. Hence, the TAP/BPTI pair represents a nice example of divergent evolution, while the relative facility of TAP synthesis could represent a good starting point to design novel synthetic analogues with improved pharmacological profiles. [ABSTRACT FROM AUTHOR]

Let ℛ be a prime ring of characteristic not equal to 2, let 풰 be Utumi quotient ring of ℛ and let 풞 be the extended centroid of ℛ . Let Δ be a generalized derivation on ℛ , and let δ 1 and δ 2 be derivations on ℛ . Let p ⁢ (v) be a multilinear polynomial on ℛ , which is non-central valued on ℛ . If δ 1 ⁢ (Δ 2 ⁢ (p ⁢ (v)) ⁢ p ⁢ (v)) = δ 2 ⁢ (Δ ⁢ (p ⁢ (v) 2)) for all v ∈ ℛ n , then we find the complete description of Δ, δ 1 and δ 2 . [ABSTRACT FROM AUTHOR]

Let R be a noncommutative prime ring of characteristic different from 2 , with right Martindale quotient ring Q r and extended centroid C. Let m , n ≥ 1 be fixed integers and F a nonzero generalized skew derivation of R. In this paper, we investigate the set S = { F (x m) x n + x n F (x m) : x ∈ R } and prove that its left annihilator in R is identically zero. Using the above result, we also study the identity F (x) x n + x n F (x) = 0 for semiprime rings. [ABSTRACT FROM AUTHOR]

Let m, n be two nonzero fixed positive integers, R a prime ring with the right Martindale quotient ring Q, G and H two generalized skew derivations of R with the same associated automorphism α of R. If G (x m + n) = H (x m) x n is an identity for R, then either R is commutative or there exists q ∈ Q such that G (x) = H (x) = q x , for any x ∈ R . [ABSTRACT FROM AUTHOR]

Let R be a prime ring of characteristic different from 2 , Q r be its right Martindale quotient ring and C be its extended centroid, α be an automorphism of R , d be a skew derivation of R with associated automorphism α , F and G be two nonzero X -generalized skew derivation of R with associated term (b , α , d) and (b ′ , α , d) , respectively, S be the set of the evaluations of f (x 1 , ... , x n) on R , where f (x 1 , ... , x n) is a non-central multilinear polynomial over C in n non-commuting variables. Let 0 ≠ v ∈ R be such that F (x) x + G (x) x v = 0 for all x ∈ S. Then one of the following statements holds : (a) f (x 1 , ... , x n) 2 is central valued on R and there exist a , a ′ ∈ Q r such that F (x) = a x , G (x) = a ′ x for any x ∈ R with a + a ′ v = 0 ; (b) v ∈ C and F = − v G. In the last part of the paper, we present some applications on the basis of the foregoing proposed result. [ABSTRACT FROM AUTHOR]

Let R be a noncommutative prime ring of characteristic different from 2, Q r be the right Martindale quotient ring of R and C = Z ( Q r) be the extended centroid of R. Suppose that π ( x 1 , ... , x n) is a noncentral multilinear polynomial over C , S = { π (r 1 , ... , r n) | r 1 , ... , r n ∈ R } , F , G and H are three generalized skew-derivations of R associated to the same automorphism α. Let h , f , g be the associated skew derivations respectively of H , F and G , such that h, f, g are commuting with α. We will provide the complete description of H , F and G , in the case F (X) G (X) = H ( X 2) , for all X ∈ S . [ABSTRACT FROM AUTHOR]