Enzymatic complexes across scales

An unprecedented opportunity to integrate ~100 years of meticulous in vitro biomolecular research is currently provided in the light of recent advances in methods to visualize closer-to-native architectures of biomolecular machines, and metabolic enzymes in particular. Traditional views of enzymes, namely biomolecular machines, only partially explain their role, organization and kinetics in the cellular milieu. Enzymes self- or hetero-associate, form fibers, may bind to membranes or cytoskeletal elements, have regulatory roles, associate into higher order assemblies (metabolons) or even actively participate in phase-separated membraneless organelles, and all the above in a transient, temporal and spatial manner in response to environmental changes or structural/functional changes of their assemblies. Here, we focus on traditional and emerging concepts in cellular biochemistry and discuss new opportunities in bridging structural, molecular and cellular analyses for metabolic pathways, accumulated over the years, highlighting functional aspects of enzymatic complexes discussed across different levels of spatial resolution.

The relationship of form and meaning: A cross-sectional study of tense and aspect in the interlanguage of learners of English as a second language

ABSTRACTThe task of all language learners is to match form and meaning. This study investigates the associations of form and meaning in the developing tense and aspect systems of adult learners of English as a second language. A cross-sectional study of 135 learners at six levels of proficiency was conducted using a cloze passage and compositions on the same topic. The interlanguage tense and aspect systems can be characterized as showing high formal accuracy, but relatively lower appropriate use across all levels. During the period when appropriate use lags behind formal accuracy, learners seem to associate form and meaning through alternative interim hypotheses related to lexical aspect and discourse function.