To make more effective use of underutilized resources, acid-solubilized collagen (ASC) and pepsin-solubilized collagen (PSC) were isolated from the skin of deep-sea redfish (Sebastes mentella) and characterized for their potential in commercial applications. The yield of ASC (47.5%) was lower compared to PSC (92.2%), but the purity of ASC was significantly higher. The intrinsic viscosity of ASC (15.9 dL/g) was greater than PSC (14.6 dL/g), indicating a higher average molecular weight of ASC on account of the high proportion of polymers of collagen. The denaturation temperatures of ASC and PSC were 16.1 and 15.7 degrees C, respectively, suggesting the triple helical structure of PSC was still predominant. The amino acid profiles of ASC and PSC were similar with lower imino acid content than most other species, which might be the reason for the lower denaturation temperature. SDS-PAGE and FTIR showed that both ASC and PSC were type I mainly with slight structure differences. ASC held its triple helical structure well, and possessed a higher extent of intermolecular cross-link. While the structure of PSC was changed slightly due to the loss of N- and C-terminus domains, the triple helical structure was still predominant as a result of the formation of more and/or stronger hydrogen bond.

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Human hexokinase 2 is an essential regulator of glycolysis that couples metabolic and proliferative activities in cancer cells. The binding of hexokinase 2 to the outer membrane of mitochondria is critical for its oncogenic activity. However, the regulation of hexokinase 2 binding to mitochondria remains unclear. Here, we report that SUMOylation regulates the binding of hexokinase 2 to mitochondria. We find that hexokinase 2 can be SUMOylated at K315 and K492. SUMO-specific protease SENP1 mediates the de-SUMOylation of hexokinase 2. SUMO-defective hexokinase 2 preferably binds to mitochondria and enhances both glucose consumption and lactate production and decreases mitochondrial respiration in parallel. This metabolic reprogramming supports prostate cancer cell proliferation and protects cells from chemotherapy-induced cell apoptosis. Moreover, we demonstrate an inverse relationship between SENP1-hexokinase 2 axis and chemotherapy response in prostate cancer samples. Our data provide evidence for a previously uncovered posttranslational modification of hexokinase 2 in cancer cells, suggesting a potentially actionable strategy for preventing chemotherapy resistance in prostate cancer.