Structure of interleukin 16 resembles a PDZ domain with an occluded peptide binding site.

The structure of a folded core of IL-16 is similar to that of intracellular protein modules called PDZ domains. IL-16 is thus the first extracellular protein found to have a PDZ-like fold. However, it does not exhibit normal peptide binding properties of PDZ domains. This is due to alterations of the structure at the 'PDZ-like binding site' of IL-16 (the GLGF cleft): the GLGF cleft of IL-16 is much smaller than those of PDZ-domains and is additionally blocked with a tryptophan side chain at its center. Our experiments indicate also that IL-16 nonspecifically aggregates in solution; but formation of a homo-tetrameric protein is not required, in contrast to previous suggestions, for its chemo-attractant activity

Contextualising Apartheid at the End of Empire: Repression, ‘Development’ and the Bantustans

This article examines the global dynamics of late colonialism and how these informed South African apartheid. More specifically, it locates the programmes of mass relocation and bantustan ‘self-government’ that characterised apartheid after 1959 in relation to three key dimensions. Firstly, the article explores the global circulation of idioms of ‘development’ and trusteeship in the first half of the twentieth century and its significance in shaping segregationist policy; secondly, it situates bantustan ‘selfgovernment’ in relation to the history of decolonisation and the partitions and federations that emerged as late colonial solutions; and, thirdly, it locates the tightening of rural village planning in the bantustans after 1960 in relation to the elaboration of anti-colonial liberation struggles, repressive southern African settler politics and the Cold War. It argues that, far from developing policies that were at odds with the global ‘wind of change’, South African apartheid during the 1960s and 1970s reflected much that was characteristic about late colonial strategy

Deciphering the Structural Basis That Guides the Oxidative Folding of Leech-derived Tryptase Inhibitor*

Protein folding mechanisms have remained elusive mainly because of the transient nature of intermediates. Leech-derived tryptase inhibitor (LDTI) is a Kazal-type serine proteinase inhibitor that is emerging as an attractive model for folding studies. It comprises 46 amino acid residues with three disulfide bonds, with one located inside a small triple-stranded antiparallel β-sheet and with two involved in a cystine-stabilized α-helix, a motif that is widely distributed in bioactive peptides. Here, we analyzed the oxidative folding and reductive unfolding of LDTI by chromatographic and disulfide analyses of acid-trapped intermediates. It folds and unfolds, respectively, via sequential oxidation and reduction of the cysteine residues that give rise to a few 1- and 2-disulfide intermediates. Species containing two native disulfide bonds predominate during LDTI folding (IIa and IIc) and unfolding (IIa and IIb). Stop/go folding experiments demonstrate that only intermediate IIa is productive and oxidizes directly into the native form. The NMR structures of acid-trapped and further isolated IIa, IIb, and IIc reveal global folds similar to that of the native protein, including a native-like canonical inhibitory loop. Enzyme kinetics shows that both IIa and IIc are inhibitory-active, which may substantially reduce proteolysis of LDTI during its folding process. The results reported show that the kinetics of the folding reaction is modulated by the specific structural properties of the intermediates and together provide insights into the interdependence of conformational folding and the assembly of native disulfides during oxidative folding