If you have been reading about MC4 receptor and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-04-30. Where a claim depends on a specific study, the study is described rather than over-claimed.
纯度评估以反相高效液相色谱为主，通过主峰面积百分比给出粗略结果，再配合电喷雾质谱核对分子量。氨基酸分析可验证组成比例，手性色谱或毛细管电泳用于检查残基构型。常见杂质包括缺失序列的短肽、氧化产物与二聚体。由于多数市售品不附带完整检验报告，独立第三方检测常被用来核实标称值。
从分子层面看，Semax 是线性七肽，没有二硫键、糖基或脂链修饰，N 端为游离氨基，C 端为游离羧基。分子含组氨酸与谷氨酸侧链，因此在水和甲醇等极性溶剂中溶解良好，在非极性溶剂中溶解有限。计算分子量约为 814 Da，与其质子化离子的质荷比吻合，可用于质谱确认。
稳定性主要由水解与氧化两条路径支配。肽键在中性或弱酸性条件下相对稳定，遇到强碱或长时间高温则明显断裂；甲硫氨酸侧链容易被氧化成亚砜，使主峰前移并拉低实际含量。金属离子、光照和反复冻融会进一步促进降解或聚集。冻干粉在低温避光条件下可存放较长时间，配制后的水溶液通常需要冷藏并尽快用完。
The proposed mechanism centres on neurotrophic signalling rather than direct receptor activation. Semax is reported to increase expression of brain-derived neurotrophic factor and nerve growth factor in several brain regions, and to shift the balance between excitatory and inhibitory neurotransmitter systems. Interaction with melanocortin receptors has been suggested because of the parent ACTH fragment. Many of these findings come from rodent studies, and the extent to which they translate to human physiology remains an open question.
Scientific literature on semax is unevenly distributed. A substantial share of published work originates from a small number of laboratories in Russia, while independent replication elsewhere is limited. Human data consist mostly of small trials with short follow-up, and several reported outcomes rely on subjective rating scales. Questions about how much intact peptide reaches the central nervous system after nasal administration, and how long it persists there, are still unresolved. The compound is best described as an active research subject rather than a settled pharmacological agent.
| Property | Value | Notes |
|---|---|---|
| 分子式 | C37H51N9O10S | 游离碱形式 |
| 等电点 | 约 6.5 | 估算值，随缓冲体系变化 |
| 主要降解途径 | 水解与氧化 | 侧链氧化最为常见 |
| 溶液储存 | 2 至 8 摄氏度避光 | 避免反复冻融 |
| 常规分析手段 | 反相色谱与质谱联用 | 氨基酸分析辅助核对 |
The mechanisms attributed to semax are inferred from animal and cell studies rather than traced to one confirmed target. The most frequently cited pathway involves increased expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal and cortical tissue. Some work points to engagement of melanocortin receptors, particularly MC4, which the parent ACTH fragment can activate. Effects on dopaminergic and serotonergic signalling have also been reported. No single account explains all observed results, and the relative weight of each pathway remains unsettled.
Published studies examine a fairly narrow set of endpoints. Rodent experiments commonly measure maze learning, infarct volume after induced ischemia, and tissue levels of neurotrophic factors. Clinical reports from Russian centres describe attention, memory and recovery scores in patients after stroke or transient ischemic attack. Most of those human studies are small and few have been repeated by independent groups. Outcome measures differ between studies, which limits direct comparison.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its design combines the ACTH(4-7) core fragment with a C-terminal Pro-Gly-Pro extension, a modification intended to improve stability and prolong activity. The molecule is hydrophilic, carries no lipid chains or glycosylation, and has a theoretical mass just over 810 daltons in its free form. All seven residues are proteinogenic amino acids, so no non-natural building blocks appear in the backbone. A free N-terminal methionine and C-terminal proline define the unmodified parent peptide.
The compound was developed during the 1980s at the Institute of Molecular Genetics in Moscow as part of research on fragments of adrenocorticotropic hormone. Early work examined short ACTH-derived sequences that retained neurotrophic effects while lacking the endocrine activity of the full hormone. Semax entered clinical use in Russia during the 1990s, where it received registration for several neurological indications. Outside that region it remained primarily a laboratory research material rather than an approved therapeutic. English-language literature on it grew more slowly and frequently cited the original Russian studies.
Terminology around the compound varies by source. It appears in catalogues and papers as Semax, as the heptapeptide ACTH(4-7)-Pro-Gly-Pro, and under various alphanumeric laboratory codes used by individual suppliers. These names refer to the same sequence but may imply different salt forms, purity grades, or counter-ions. Peptide databases usually list the free base mass, while product descriptions sometimes report acetate or trifluoroacetate salts with a different formula weight. Because naming conventions for research peptides are not standardised across vendors, checking the declared sequence and measured mass is more reliable than relying on a trade name alone.
=== Congenital Disorders of Amino Acid Metabolism === Newborn screening originated with an amino acid disorder, phenylketonuria (PKU), which can be easily treated by dietary modifications, but causes severe Intellectual disability if not identified and treated early. Robert Guthrie introduced the newborn screening test for PKU in the early 1960s. With the knowledge that PKU could be detected before symptoms were evident, and treatment initiated, screening was quickly adopted around the world. Ireland was the first country in the world to introduce a nationwide screening programme in February 1966, Austria started screening the same year and England in 1968. Other congenital disorders of amino acid metabolism tested for on the newborn screening include Tyrosinemia and Maple Syrup Urine Disorder.
=== The Lancet COVID-19 Commission task force === In November 2020, Richard Horton, editor of The Lancet, appointed economist Jeffrey Sachs as chair of its COVID-19 Commission, with wide-ranging goals relating to the virus and pandemic. Sachs set up a number of task forces, including one on the origins of the virus. Sachs appointed Peter Daszak, a colleague of Sachs' at Columbia, to head this task force, two weeks after the Trump administration prematurely ended a federal grant supporting a project led by Daszak, EcoHealth Alliance, which worked with the Wuhan Institute of Virology. This appointment was criticised as creating a conflict of interest, for instance by Richard Ebright, chemical biologist at Rutgers University, who called the commission an "entirely Potemkin commission" in the National Review. Daszak stated that the task force was formed to "conduct a thorough and rigorous investigation into the origins and early spread of SARS-CoV-2". The task force has twelve members with backgrounds in One Health, outbreak investigation, virology, lab biosecurity and disease ecology. The task force planned to analyse scientific findings and did not plan to visit China. However, as Sachs became increasingly drawn to the lab leak theory, he came into conflict with Daszak and his task force. In June 2021, The Lancet announced that Daszak had recused himself from the commission. On 25 September 2021, the task force work was folded after procedural concerns and a need to broaden its scope to examine transparency and government regulation of risky laboratory research.
=== Microfibrilated cellulose === Micro cellulose (MFC) is a type of nanocellulose that is more heterogeneous than cellulose nanofibers or nanocrystals as it contains a mixture of nano- and micro-scale particles. The term is sometimes misused to refer to cellulose nanofibers instead.
The Basuto's lack of cooperation gave rise to calls for Basutoland's disannexation within the Cape Parliament. Eager to restore pre-war order, Scanlen invited Major General Charles George Gordon to Basutoland. Gordon had built a reputation as a capable administrator and an expert negotiator. He proposed replacing the magisterial system, granting the Basuto chiefs de facto autonomous rule. The proposal was rejected by John X. Merriman as unenforceable, citing the absence of unity among the Basuto. Merriman persuaded Gordon to stay in the Cape for an additional year. Sauer and Gordon then traveled to Basutoland in September 1882, Gordon was convinced that he could resolve the conflict if he were to enter negotiations with Masopha. On 16 September, Sauer held a private meeting with Letsie I and Lerotholi, and consented to the Basuto chiefs' proposal to assemble a force against Masopha. On 25 September, Gordon departed for a meeting with Masopha at Thaba Bosiu, at the same time Lerotholi had completed preparations to launch an assault on the stronghold. During his meeting with Masopha, Gordon disobeyed written instructions given to him by Sauer. Furthermore, Masopha intentionally prolonged the negotiations, thus thwarting Lerotholi's assault on the mountain. Gordon departed Thaba Bosiu without having achieved his objective and resigned soon afterwards. Lerotholi felt humiliated by the incident, which developed into a long-lasting rivalry between him and his uncle.
Sources: en.wikipedia.org
== Remediation strategies == A relatively small volume of NAPL can create toxic groundwater conditions, and NAPLs can remain in the subsurface, continually polluting groundwater, for decades or even centuries. Moreover, NAPLs are difficult to detect, particularly because of their multi-phase behavior. As a result, detection strategies, in addition to remediation strategies, are important in the effort to remove NAPLs from the environment. In this sense, it is important to quantify the geographic and phase distributions of NAPLs in addition to where they have been and where they may be going. In order to determine site-specific characteristics e.g. soil material and water table parameters, drill cuttings and cores can be used. Soil gas surveys can be used as a preliminary screening procedure to determine the extent of contamination due to volatile components. Some of the current strategies to detect and analyze NAPL presence include gas chromatography, high pressure liquid chromatography, and time domain reflectometry. That said, additional research in this area is warranted.
== Amateur career == Helton attended Central High School in Knoxville, Tennessee and was a letterman in football and baseball. In football, he posted 2,772 total yards as a quarterback. In baseball, as a senior, Helton had a .655 batting average and 12 home runs and was named the Regional Player of the Year. Baseball America named him an All-American his senior season. He was named the Gatorade Player of the Year for football and baseball in Tennessee. Helton was drafted in the second round (55th overall) by the San Diego Padres in the 1992 MLB draft. He did not sign, instead choosing to attend college.
The special forces site, located near a compound associated with Mullah Omar, was described as one of Akhundzada's most trusted units. Afghan locals also reported an airstrike in Spin Boldak District, while armed clashes resumed between Taliban forces and Pakistani border guards in Khost. However, a Taliban spokesperson claimed that no one had been hurt in the airstrikes and that they had caused only limited damage to a drug rehabilitation centre and an empty container. A police constable was injured while repelling a militant attack on a police post in Dera Ismail Khan District.
Sources: en.wikipedia.org
Additionally, recent research by anthropologist and archaeologist Steven Kuhn from the University of Arizona is argued to support that this division of labor did not exist prior to the Upper Paleolithic and was invented relatively recently in human pre-history. Sexual division of labor may have been developed to allow humans to acquire food and other resources more efficiently. Possibly there was approximate parity between men and women during the Middle and Upper Paleolithic, and that period may have been the most gender-equal time in human history. Archaeological evidence from art and funerary rituals indicates that a number of individual women enjoyed seemingly high status in their communities, and it is likely that both sexes participated in decision making. The earliest known Paleolithic shaman (c. 30,000 BP) was female. Jared Diamond suggests that the status of women declined with the adoption of agriculture because women in farming societies typically have more pregnancies and are expected to do more demanding work than women in hunter-gatherer societies. Like most modern hunter-gatherer societies, Paleolithic and Mesolithic groups probably followed a largely ambilineal approach. At the same time, depending on the society, the residence could be virilocal, uxorilocal, and sometimes the spouses could live with neither the husband's relatives nor the wife's relatives at all. Taken together, most likely, the lifestyle of hunter-gatherers can be characterized as multilocal.
The technique Reddy invented is now widely applied in the characterization of petroleum in environmental samples as well as in analyses of other complex organic mixtures, and, because of it, GCxGC has transitioned from “a niche qualitative analysis tool to a robust quantitative technique.” For this innovative work, Reddy was awarded the Clair C. Patterson Award in 2014 by the Geochemical Society for "an innovative breakthrough in environmental geochemistry of fundamental significance within the last decade, particularly in service to society. To be viewed as innovative, the work must show a high degree of creativity and/or be a fundamental departure from usual practice while contributing significantly to understanding in environmental geochemistry." Reddy's first investigation into oil spills employing the new method was at the West Falmouth Harbor of Massachusetts, where the barge Florida had run aground in 1969, spilling 175,000 gallons of heating oil. Reddy and his team studied the area from 1999 to 2008, identifying chemical and biological effects that persisted even after 30 years. According to geologist and biogeoscientist Timothy Eglinton, at the time Reddy received the Patterson Award, the "string of papers" he and his team members had published "on this oil spill ... collectively represent[ed] amongst the most comprehensive, sustained and multifaceted investigations of the environmental fate of a single petroleum spill" published to date, thanks to Reddy's use of the novel GCxGC method he had pioneered.
The Canadas were the main front in the War of 1812 between the United States and the United Kingdom. Peace came in 1815; no boundaries were changed. Immigration resumed at a higher level, with over 960,000 arrivals from Britain between 1815 and 1850. New arrivals included refugees escaping the Great Irish Famine as well as Gaelic-speaking Scots displaced by the Highland Clearances. Infectious diseases killed between 25 and 33 percent of Europeans who immigrated to Canada before 1891. The desire for responsible government resulted in the abortive Rebellions of 1837. The Durham Report subsequently recommended responsible government and the assimilation of French Canadians into English culture. The Act of Union 1840 merged the Canadas into a united Province of Canada and responsible government was established for all provinces of British North America east of Lake Superior by 1855. The signing of the Oregon Treaty by Britain and the United States in 1846 ended the Oregon boundary dispute, extending the border westward along the 49th parallel. This paved the way for British colonies on Vancouver Island (1849) and in British Columbia (1858). The Anglo-Russian Treaty of Saint Petersburg (1825) established the border along the Pacific coast, but, even after the US Alaska Purchase of 1867, disputes continued about the exact demarcation of the Alaska–Yukon and Alaska–British Columbia border.
Sources: en.wikipedia.org
电喷雾或基质辅助激光解吸电离质谱是常用手段，测得的质子化离子质荷比可换算为分子量。结果与理论值落在合理误差内，才支持结构一致的判断。
甲硫氨酸侧链含硫醚，在氧气、光照或金属离子存在时容易被氧化。氧化产物极性略增，常在色谱图上表现为主峰之前的肩峰或前伸峰。
通常建议冷藏避光，并在较短时间内使用。不存在适用于所有配方的统一期限，具体取决于浓度、缓冲体系与容器材质。
Semax is based on the ACTH(4-10) fragment, a seven-amino-acid segment of adrenocorticotropic hormone. The synthetic peptide retains the core sequence while removing regions associated with endocrine activity. This modification is intended to isolate effects on the nervous system.