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SS-31 Peptide & Mitochondrial Optimization



So today, we are going to delve into a topic previously mentioned in last week's post: SS-31 peptide. To establish a foundation, we will provide a simplified overview of mitochondria's structure. This is crucial as understanding the various components of the mitochondria affected by SS-31 requires knowledge of their structure.


Structurally, mitochondria consist of an outer membrane enclosing the organelle and an inner membrane that forms numerous folds called cristae, thereby increasing its surface area for biochemical reactions. Within the inner membrane lies the mitochondrial matrix, a fluid-filled space containing mitochondrial DNA, ribosomes, enzymes, and other essential components. The inner membrane, highly impermeable, contains proteins integral to oxidative phosphorylation, including the electron transport chain complexes (I to IV) and ATP synthase.


These complexes, designated as complexes I to IV within the inner mitochondrial membrane, each serve specific functions in facilitating the transfer of electrons derived from NADH and FADH2.


Commencing with Complex I (NADH Dehydrogenase): Complex I, also referred to as NADH dehydrogenase, catalyzes the transfer of electrons from NADH to ubiquinone (coenzyme Q). As electrons traverse through complex I, energy is released and utilized to pump protons (H⁺ ions) across the inner mitochondrial membrane from the mitochondrial matrix to the intermembrane space.


Moving on to Complex II (Succinate Dehydrogenase): Complex II, also known as succinate dehydrogenase, plays a pivotal role by transferring electrons from FADH2 (derived from the citric acid cycle) directly to coQ. Notably, Complex II does not pump protons across the membrane like complex 1, yet it contributes electrons to the electron transport chain. Electrons from both complex 1 and complex 2 are essentially transferred to coQ. Consequently, we proceed to complex 3.


Complex III receives electrons from coQ and transfers them to cytochrome c while pumping additional protons into the intermembrane space. Cytochrome c facilitates electron transfer from complex III, leading to its reduction and diffusion through the intermembrane space, ultimately delivering electrons to complex IV. In complex IV (cytochrome c oxidase), cytochrome c transfers its electrons to molecular oxygen (O2), the final electron acceptor in the electron transport chain. This transfer of electrons culminates in the reduction of oxygen to water. The electron movement through cytochrome c, and subsequently to complex IV, drives proton pumping across the inner mitochondrial membrane, contributing to the establishment of a proton gradient essential for ATP synthesis by ATP synthase.


It is crucial to note that reactive oxygen species (ROS) are generated as a byproduct of ATP production. ROS comprises highly reactive oxygen-containing molecules such as superoxide radicals (O2•−), hydrogen peroxide (H2O2), and hydroxyl radicals (•OH). If left unchecked, these molecules can damage cellular components, including proteins, lipids, and DNA.

A deeper understanding of ROS generation elucidates the significance of SS-31 peptide. One primary mechanism involves electron leak, where a fraction of electrons prematurely leaks from the electron transport chain, primarily at complex I and complex III. These leaked electrons react with molecular oxygen, resulting in the formation of superoxide radicals. Addressing ROS production is imperative as it can lead to lipid peroxidation, particularly of critical lipids like cardiolipin within the inner mitochondrial membrane.

Cardiolipin (CL), a key phospholipid constituent of the inner mitochondrial membrane, plays a pivotal role in maintaining membrane potential and architecture. Moreover, CL provides structural and functional support to proteins involved in mitochondrial respiration. However, alterations in CL composition and peroxidation have been implicated in various human diseases, notably metabolic dysfunction and insulin resistance.


Mitigating ROS-induced damage and preserving the integrity of cardiolipin are where SS-31 peptide demonstrates its efficacy. SS-31 peptide once administered, primarily binds to the inner mitochondrial membrane, and it possesses a dimethyltyrosine residue enabling scavenging of oxyradicals and inhibition of lipid peroxidation within the IMM. This characteristic has led to its classification as a mitochondrial antioxidant peptide.


Stabilizing the lipid constructs within the IMM allows for the support of the electron transport chain, facilitating ATP production. Hence, maintaining the proper fluidity, integrity, and composition of the IMM is crucial for optimal ATP production and ROS regulation. SS-31's ability to reduce mitochondrial ROS, prevent lipid peroxidation, and inhibit the opening of the mitochondrial permeability transition pore (mPTP) underscores its significance in preserving mitochondrial function and preventing cell death.


On a broader scale, SS-31 peptide's therapeutic potential extends to numerous disease settings characterized by mitochondrial dysfunction, including neuroinflammation, neurodegeneration, diabetes, and age-related diseases. It has also been shown to improve exercise performance within 5 days in one study. While the mechanisms of action for SS-31 peptide are promising, further research is warranted to fully elucidate its therapeutic implications.


Only ever work with licensed medical professionals.

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