2 results for Ahn, S

  • Structure-function relationships in a bacterial DING protein

    Ahn, S; Moniot, S; Elias, M; Chabriere, E; Kim, D; Scott, George (2007-07-24)

    Journal article
    The University of Auckland Library

    A recombinant DING protein from Pseudomonas fluorescens has been previously shown to have a phosphate-binding site, and to be mitogenic for human cells. Here we report the three-dimensional structure of the protein, confirming a close similarity to the "Venus flytrap" structure seen in other human and bacterial phosphate-binding proteins. Site-directed mutagenesis confirms the role of a key residue involved in phosphate binding, and that the mitogenic activity is not dependent on this property. Deletion of one of the two hinged domains that constitute the Venus flytrap also eliminates phosphate binding whilst enhancing mitogenic activity. (c) 2007 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

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  • Second language learners' beliefs about grammar instruction and error correction

    Loewen, S; Li, Shaofeng; Fei, F; Thompson, A; Nakatsukasa, K; Ahn, S; Chen, X (2009)

    Journal article
    The University of Auckland Library

    Learner beliefs are an important individual difference in second language (L2) learning. Furthermore, an ongoing debate surrounds the role of grammar instruction and error correction in the L2 classroom. Therefore, this study investigated the beliefs of L2 learners regarding the controversial role of grammar instruction and error correction. A total of 754 L2 students at an American university completed a questionnaire consisting of 37 Likert-scale items and 4 open-ended prompts. The quantitative items were submitted to a factor analysis, which identified 6 underlying factors (efficacy of grammar, negative attitude toward error correction, priority of communication, importance of grammar, importance of grammatical accuracy, and negative attitude toward grammar instruction). These factors were then used to investigate differences in beliefs among learners studying different target languages. In addition, themes emerging from the qualitative data were identified. The results indicate that among learners studying English as a second language and those studying a foreign language, there were varied beliefs about grammar instruction and error correction.

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