Spectroscopic and calorimetric methods were employed to assess the stability and the folding aspect of a novel recombinant alkaline-stable lipase KV1 from Acinetobacter haemolyticus under varying pH and temperature. Data on far ultraviolet-circular dichroism of recombinant lipase KV1 under two alkaline conditions (pH 8.0 and 12.0) at 40 °C reveal strong negative ellipticities at 208, 217, 222 nm, implying its secondary structure belonging to a α + β class with 47.3 and 39.0% ellipticity, respectively. Results demonstrate that lipase KV1 adopts its most stable conformation at pH 8.0 and 40 °C. Conversely, the protein assumes a random coil structure at pH 4.0 and 80 °C, evident from a strong negative peak at ∼ 200 nm. This blue shift suggests a general decline in enzyme activity in conjunction with the partially or fully unfolded state that invariably exposed more hydrophobic surfaces of the lipase protein. The maximum emission at ∼335 nm for pH 8.0 and 40 °C indicates the adoption of a favorable protein conformation with a high number of buried tryptophan residues, reducing solvent exposure. Appearance of an intense Amide I absorption band at pH 8.0 corroborates an intact secondary structure. A lower enthalpy value for pH 4.0 over pH 8.0 and 12.0 in the differential scanning calorimetric data corroborates the stability of the lipase at alkaline conditions, while a low K_m (0.68 ± 0.03 mM) for tributyrin verifies the high affinity of lipase KV1 for the substrate. The data, herein offer useful insights into future structure-based tunable catalytic activity of lipase KV1.

光谱和量热法用于评估溶血不动杆菌的新型重组碱性稳定脂肪酶KV1的稳定性和折叠方面在变化的pH值和温度下。重组脂肪酶KV1在40°C的两个碱性条件下（pH 8.0和12.0）的远紫外圆二色性数据显示在208、217、222 nm处具有强负椭圆率，这表明其二级结构属于α+β类，为47.3椭圆率分别为39.0％。结果表明，脂肪酶KV1在pH 8.0和40°C下采用最稳定的构象。相反，该蛋白质在pH 4.0和80°C时呈无规卷曲结构，从〜200 nm处的强负峰可见一斑。这种蓝移表明酶活性的普遍下降以及部分或完全展开的状态，而这种状态始终会暴露出脂肪酶蛋白的更多疏水表面。pH为8时在〜335 nm处的最大发射。0和40°C表示采用了具有大量隐性色氨酸残基的良好蛋白质构象，从而减少了溶剂暴露。在pH 8.0处出现强烈的酰胺I吸收带，证实了完整的二级结构。在差示扫描量热数据中，pH 4.0的焓值低于pH 8.0和12.0，这证实了脂肪酶在碱性条件下的稳定性，而K值低甘油三丁酸酯的_m（0.68±0.03 mM）验证了脂肪酶KV1对底物的高亲和力。本文中的数据提供了对脂肪酶KV1未来基于结构的可调催化活性的有用见解。