Technical analysis of packaging storage and antifreeze melting

Lactate dehydrogenase (LDH), as a key enzyme in the glucose metabolism pathway, is widely used in clinical myocardial injury detection and cellular metabolism research. The catalytic efficiency directly depends on the integrity of the protein's spatial conformation. In practical applications, small deviations in storage conditions often lead to a significant decrease in lactate dehydrogenase activity, which in turn affects the accuracy of detection data and the reproducibility of experiments. Among them, packaging storage and avoiding repeated freezing and thawing are two important conditions for maintaining the stability of lactate dehydrogenase, which have clear biochemical basis behind them.

Lactate dehydrogenase

Molecular Structure Stability and Freeze Thaw Damage Mechanism

Lactate dehydrogenase is an oligomeric protein composed of four subunits bound by non covalent bonds, and its active center depends on the spatial arrangement between subunits. During the low-temperature freezing process, solvent water molecules form ice crystals, and the mechanical shear force generated by volume expansion can directly break the connections between subunits, leading to the dissociation of the quaternary structure or deformation of the active center.

Repeated freeze-thaw cycles can exacerbate this physical damage. Each "freeze melt" cycle causes irreversible denaturation and aggregation of some lactate dehydrogenase molecules. As the number of cycles increases, the proportion of complete enzyme molecules with catalytic function decreases exponentially. In addition, freeze-thaw can cause phase separation in the buffer system, alter local pH values and ionic strength, and further accelerate the inactivation process of lactate dehydrogenase. Clinical data shows that reagents that have undergone three or more repeated freeze-thaw cycles often have residual activity less than 60% of their initial value, which can easily lead to false negatives or low quantification in test results.

Standardized packaging operation process

To avoid the loss of activity caused by repeated freeze-thaw cycles, implementing small volume packaging is a common standard operating procedure in the industry. The specific implementation steps for lactate dehydrogenase are as follows:

1. Environmental control: The packaging operation should be carried out in an ice bath environment at 0-4 ℃ to suppress the thermal denaturation of enzymes.

2. Container selection: Choose sterile, low protein adsorption centrifuge tubes or reagent bottles.

3. Volume planning: Determine the packaging volume based on the amount used in a single experiment, ensuring that the single tube reagent is used up in one go and there is no residual freezing.

4. Quick freezing: After packaging is completed, immediately place it in a -20 ℃ (short-term storage) or -80 ℃ (long-term storage) environment for quick freezing.

5. Identification management: The container surface should be clearly labeled with the product name, batch number, concentration, packaging date, and expiration date, and a traceable management ledger should be established.

Technical specifications for retrieval and thawing

In addition to storage methods, standardized operations in the retrieval process are also crucial. When removing lactate dehydrogenase preparations from low-temperature environments, they should be slowly thawed in an ice box. It is strictly prohibited to let them sit at room temperature or use heating to assist in melting, in order to avoid protein precipitation caused by severe temperature fluctuations. After complete thawing, gently invert and mix well. Avoid vigorous shaking or vortex mixing to prevent shear forces from damaging the enzyme molecule structure. If multiple tubes of reagents are required for the experiment, they should be taken out one by one as needed to avoid unnecessary temperature changes in unused tubes.

Hubei Xindesheng Material Technology Co., Ltd. has been dedicated to the research and production of diagnostic enzyme reagents since its establishment in 2005. The company strictly follows GMP standards and significantly improves the thermal stability and freeze-thaw tolerance of its products by optimizing purification processes and formulation systems. We recommend that users strictly follow the packaging and storage strategy when using high-purity lactate dehydrogenase preparations to fully utilize product performance and ensure the accuracy and reliability of clinical diagnosis and scientific research data.