Journal of Endocrinology and Metabolism, ISSN 1923-2861 print, 1923-287X online, Open Access
Article copyright, the authors; Journal compilation copyright, J Endocrinol Metab and Elmer Press Inc
Journal website http://www.jofem.org

Original Article

Volume 7, Number 1, February 2017, pages 18-24

The Impact of Diabetes Mellitus on Oxygen Utilization by Complex IV: Preliminary Insights

Figures

Figure 1.
Figure 1. Cytochrome c oxidase. (a) The 13 subunits of one monomer of bovine COX (22): subunit, I (white), II (red) and III (blue) IV (yellow), V (pink), VI (green; extra-membrane) VII (light blue), VIII (purple), IX (gray), X (orange), XI (brown), XII (dark green) and XIII (dark brown). The white bracket shows the approximate position of the membrane. (b) A typical dimer (two identical monomers) of mammalian COX. One monomer is colored yellow and the other light blue; for ease of reference subunit II of the former is shown in red. The structures in both “a” and “b” are tilted slightly. (c) A section of the electron transport chain showing complexes III and IV. Cytochrome c (cty c) picks up electrons from complex III and delivers them to complex IV.
Figure 2.
Figure 2. Eadie-Hofstee plots. (a) Eadie-Hofstee plots generated from the polarographic assay of COX within rat liver mitochondria. Typical control (blue). Diabetic at 1 month (red). Diabetic at 2 months (green). Diabetic at 3 months (purple). (b) Eadie-Hofstee plots generated from the polarographic assay of COX within rat kidney mitochondria. Typical control (blue). Diabetic at 1 month (red). Diabetic at 2 months (green). Diabetic at 3 months (purple). For all experiments the final mitochondrial concentration was 0.2 mg/mL; the substrate (cytochrome c) concentration was 6.8 - 680 μM.
Figure 3.
Figure 3. SDS-PAGE of liver and kidney (d-f) mitochondria. (a-c) Liver. SDS-PAGE of mitochondria from control and diabetic rats. (a) Lane 1: molecular weight standards (7.1 - 209 kd); lane 2: control; lane 3: diabetic rats 1 month. (b) Lane 1: control; lane 2: diabetic rats 2 months; lane 3: diabetic rats 3 months. (c) Densitometric analysis of the SDS gels shown in A and B. In all three cases, the blue traces are from the controls and the red are generated from the diabetics. (d-f) Kidney. SDS-PAGE of kidney mitochondria from control and diabetic rats. (d) Lane 1: molecular weight standards (7.1 - 209 kd); lane 2: control; lane 3: diabetic rats 1 month. (e) Lane 1: control; lane 2: diabetic rats 2 months; lane 3: diabetic rats 3 months. (f) Densitometric analysis of the SDS gels shown in (a) and (b). In all three cases, the blue traces are from the controls and the red are generated from the diabetics.

Tables

Table 1. Summary Km and Vmax for Liver Mitochondria
 
Low affinity Vmax (nmol O2/min)High affinity Vmax (nmol O2/min)Low affinity Km (M × 10-6)High affinity Km (M × 10-8)
The table summarizes the Km and Vmax values deduced from the Eadie-Hofstee plots which were generated from the polarographic assays of liver mitochondria from control and diabetic rats. The final mitochondrial concentration was 0.2 mg/mL. Experiments were done in triplicate for groups of five rats.
Control (1 month)4,4002,20020.6
Diabetic (1 month)7,200-11-
Control (2 months)7,5001,700113
Diabetic (2 months)14,0002,500331
Control (3 months)5,1001,50044
Diabetic (3 months)6,250-3-

 

Table 2. Summary of Km and Vmax for Kidney Mitochondria
 
Low affinity Vmax (nmol O2/min)High affinity Vmax (nmol O2/min)Low affinity Km (M × 10-6)High affinity Km (M × 10-8)
The table summarizes the Km and Vmax values deduced from the Eadie-Hofstee plots which were generated from the polarographic assays of kidney mitochondria from control and diabetic rats. The final mitochondrial concentration was 0.2 mg/mL. Experiments were done in triplicate for groups of five rats.
Control (1 month)6,0002,0009.513
Diabetic (1 month)2,470470189
Control (2 months)11,8002,8001.510
Diabetic (2 months)13,1802,6001.66
Control (3 months)4,1001,400513
Diabetic (3 months)3,500-4.8-