Jin Kyun Kim

Why metalloenzymes often show dramatic changes in their catalytic activity when subjected to chemically similar but non-native metal substitutions is a long-standing puzzle. Here, we report on the catalytic roles of metal ions in a model metalloenzyme system, human carbonic anhydrase II (CA II). Through a comparative study on the intermediate states of the zinc-bound native CA II and non-native metal-substituted CA IIs, we demonstrate that the characteristic metal ion coordination geometries (te

Granulocyte macrophage colony stimulating factor (GM-CSF) is a potent hematopoietic cytokine, which stimulates stem cell proliferation in the bone marrow. We now report that GM-CSF receptors expressed on neural progenitor cells and can mediate a biological response in cells to treat with GM-CSF treated neural progenitor cells exhibited a proliferative response and a marked decrease in terminal differentiation to mature neuron or astrocytes. GM-CSF treatment also suppressed neural progenitor cell

Human carbonic anhydrase II (hCA II) is a zinc metalloenzyme that catalyzes the reversible hydration/dehydration of CO 2 /HCO 3 − . Although hCA II has been extensively studied to investigate the proton-transfer process that occurs in the active site, its underlying mechanism is still not fully understood. Here, ultrahigh-resolution crystallographic structures of hCA II cryocooled under CO 2 pressures of 7.0 and 2.5 atm are presented. The structures reveal new intermediate solvent states of hCA

Human carbonic anhydrase II (hCA II) is a zinc metalloenzyme that catalyzes the reversible hydration/dehydration of CO₂/HCO₃^-. Although hCA II has been extensively studied to investigate the proton-transfer process that occurs in the active site, its underlying mechanism is still not fully understood. Here, ultrahigh-resolution crystallographic structures of hCA II cryocooled under CO₂ pressures of 7.0 and 2.5 atm are presented. The structures reveal n

Enzymes are catalysts of biological processes. Significant insight into their catalytic mechanisms has been obtained by relating site-directed mutagenesis studies to kinetic activity assays. However, revealing the detailed relationship between structural modifications and functional changes remains challenging owing to the lack of information on reaction intermediates and of a systematic way of connecting them to the measured kinetic parameters. Here, a systematic approach to investigate the eff

Water plays an essential role in enzyme structure, stability, and the substantial rate enhancement of enzyme catalysis. However, direct observations linking enzyme catalysis and active-site water dynamics pose a significant challenge due to experimental difficulties. By integrating an ultraviolet (UV) photolysis technique with temperature-controlled X-ray crystallography, we track the catalytic pathway of carbonic anhydrase II (CAII) at 1.2 Å resolution. This approach enables us to construct mol

Crystal polymorphism serves as a strategy to study the conformational flexibility of proteins. However, the relationship between protein crystal packing and protein conformation often remains elusive. In this study, two distinct crystal forms of a green fluorescent protein variant, NowGFP, are compared: a previously identified monoclinic form (space group C2) and a newly discovered orthorhombic form (space group P2₁2₁2₁). Comparative analysis reveals that both cr

Carbonic anhydrase II (CAII) is one of the most efficient enzymes known, catalyzing the reversible hydration of CO₂ to regulate pH and facilitate CO₂ transport in biological systems. Its exceptional catalytic rate depends on a highly ordered active site composed of a Zn²⁺ ion and a hydrogen-bonded water network that supports substrate binding, proton transfer, and product release. Among the residues maintaining this network, Thr200 plays a crucial role by stabili

Human carbonic anhydrase II (hCA II) is a zinc metalloenzyme that catalyzes the reversible hydration/dehydration of carbon dioxide and water to bicarbonate and a proton. In this study, ultrahighresolution crystallographic structures of hCA II cryocooled under various CO2 internal pressures are presented. The structures reveal new intermediate solvent states of hCA II that provide crystallographic snapshots during the restoration of the proton-transfer water network in the active site. Based on t