{
  "id": 9480032,
  "title": "Conformational Barrier-Driven Flux Redistribution across Competing Catalytic Pathways Unifies Diverse Enzyme Kinetic Regimes",
  "url": "https://urgent.news/2026/09/23/conformational-barrier-driven-flux-redistribution-across-competing",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-23T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.09.21.753117v1?rss=1"
  },
  "original_language": "en",
  "account": "Enzymes are crucial for biological processes, facilitating chemical reactions necessary for metabolism, signaling, transport, and regulation. To comprehend enzyme activity, we must connect molecular structure and conformational dynamics to observable reaction kinetics. Classical Michaelis-Menten kinetics describes a single, dominant catalytic pathway, while conformational-selection, allosteric, dynamic-disorder models consider additional complexity due to conformational exchange and heterogeneous catalytic states. Observations show that enzyme activity can change with concentration, leading to cooperative or sigmoidal responses, transitions between different turnover regimes, and intermittent single-molecule behavior. Traditionally, these phenomena are explained using separate kinetic models, but their relationship within a unified framework remains unclear.\n\nIn this study, researchers propose a minimal conformational free-energy landscape, depicting a series of enzyme states that interconvert and involve competing catalytic routes. They explore how substrate availability and conformational barriers can redistribute catalytic flux between slower and faster pathways, impacting both pathway occupancy and turnover times. By employing stochastic Gillespie simulations alongside deterministic mean-first-passage-time analysis, they demonstrate that varying parameter regimes can generate low- and high-turnover states, concentration-dependent kinetic crossovers, burst-halt intermittency, and responses akin to Michaelis-Menten kinetics or allosteric behavior. Essentially, the same underlying landscape can generate a range of kinetic behaviors, depending on how conformational exchange and substrate capture partition catalytic flux. The study also explains how finite substrate windows can obscure the underlying bimodal behavior. Together, these findings offer a physically interpretable framework that links conformational dynamics, pathway selection, and experimentally observed enzyme kinetics.",
  "summary": "Enzymes are central to biological function, catalyzing the chemical transformations that sustain metabolism, signalling, molecular transport, and cellular regulation. Understanding their catalytic activity requires connecting molecular structure and conformational dynamics to measurable reaction kinetics. Classical Michaelis--Menten kinetics describes turnover through a dominant catalytic pathway…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}