PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “MSC”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2026

Overcoming Immunological Barriers in MSC-Derived Insulin-Producing Cells through CRISPR-Based Hypoimmunogenic Engineering and Translational Perspectives for Type 1 Diabetes.

Mesenchymal stromal cell (MSC)-derived insulin-producing cells (IPCs) represent an emerging strategy for β-cell replacement in type 1 diabetes mellitus (T1DM) owing to their differentiation potential, intrinsic immunomodulatory properties, and lower tumorigenic risk compared with pluripotent stem cell-derived platforms. However, accumulating evidence indicates that differentiation-associated immunogenicity, context-dependent immune recognition, and recurrent autoimmune responses may substantially limit long-term graft survival and therapeutic durability following transplantation. This review critically examines the immunological barriers associated with MSC-derived IPCs, including altered MHC expression, susceptibility to alloimmune and autoimmune-mediated rejection, and potential reactivation of autoreactive immune memory. We discuss the application of CRISPR-based hypoimmunogenic engineering strategies targeting antigen presentation pathways, NK-cell activation, and immune checkpoint modulation to generate more immune-evasive MSC-derived IPCs while preserving β-cell functionality. By integrating insights from T1DM immunopathogenesis, MSC biology, genome editing, and translational immunology, we propose a framework linking immune engineering with controlled differentiation, functional maturation, and long-term safety evaluation. In parallel, we comparatively position MSC-derived IPCs alongside clinically advancing iPSC-derived β-cell platforms to highlight their distinct translational niche, including potential advantages related to safety, immunomodulatory capacity, manufacturing accessibility, and scalability, while acknowledging the superior functional maturity and clinical progression currently demonstrated by iPSC-derived systems. Finally, we discuss key translational challenges, including genomic stability, immune-evasion durability, GMP-compliant manufacturing, and the need for rigorous functional and immunological benchmarking prior to clinical application of hypoimmunogenic MSC-derived IPC therapies in T1DM.

Humans↗
PubMed2026

Methyltransferase METTL1 regulates MSC mRNA stability via m7G modification in acute pancreatitis.

Acute pancreatitis (AP) is a serious inflammatory disease with significant morbidity, yet its underlying molecular mechanisms remain incompletely understood. This study reveals a novel epitranscriptomic pathway in AP pathogenesis centered on METTL1-mediated N7-methylguanosine (m7G) RNA modification. We found that METTL1 expression and global m7G levels were significantly elevated in serum from AP patients, pancreatic tissues of sodium taurocholate-induced AP mice, and in vitro models of LPS-polarized macrophages and STC-injured pancreatic acinar cells. Through integrated multi-omics analysis combining m7G methylome mapping and transcriptome profiling, we identified Musculin (MSC) as a key target whose mRNA stability is enhanced by METTL1-mediated m7G modification. Functional experiments demonstrated that MSC upregulation activates TNF signaling through phosphorylation of NF-κB, JNK, and MAPK proteins, thereby promoting macrophage M1 polarization and pancreatic acinar cell injury. The pathological significance of this pathway was confirmed in vivo, where pancreas-targeted knockdown of Mettl1 significantly attenuated AP severity. Furthermore, mechanistic studies using a catalytic-dead METTL1 mutant established that both the methyltransferase activity of METTL1 and subsequent TNF signaling activation are essential for driving inflammatory responses. Our findings delineate a previously unrecognized METTL1-m7G-MSC-TNF signaling axis that promotes AP progression, highlighting the therapeutic potential of targeting METTL1-mediated epitranscriptomic modification in inflammatory diseases.

Animals↗
PubMed2026

PIP3 antagonist as a molecular regulator in MSC-derived cardiomyocytes: Potential in vitro therapeutic implications for conotruncal heart defects.

Conotruncal heart defects (CTDs) account for approximately one-third of all congenital heart defects. Elevated levels of phosphatidylinositol (3,4,5)-trisphosphate (PIP3) may contribute to CTD pathogenesis. PIP3 plays a pivotal role in mechanotransduction-based biological processes and remodeling of cardiac cytoskeletal proteins. Here, we aimed to evaluate the efficacy of the 322PESB derivative compound as a molecular regulator that antagonizes PIP3 binding pleckstrin homology (PH) domain of the Akt protein using mesenchymal stem cell-derived cardiomyocyte. Human adipose-derived MSCs (Ad-MSCs) were isolated. Immunophenotypic features of the hAd-MSCs were characterized according to minimal criteria of the international society for cellular therapy (ISCT) including immunophenotyping and trilineage differentiation potential. Subsequently, the differentiated hAd-MSCs were cultured in cardiomyogenesis-inducing medium. Successfully differentiated cardiomyocytes were assessed by measuring the expression levels of cardiomyocyte-specific genes using RT-qPCR. PIP3-primed cardiomyocytes were treated with 10 and 30 μmol/L of a 322PESB derivative molecule. The results showed a typical MSCs with high expression levels of CD73 (77.55%), CD90 (87.59%) and CD105 (91.88%) and that was accompanied by low expression levels of CD34 (0.59%) and CD45 (1.78%). After 21 days of MSC culture, cardiomyocyte-like cells with prominent striations were observed. Subsequent confirmation by RT-qPCR quantification of ADRB1 and MLC2a expression levels showed an average increase of 2.9-fold and 2.1-fold, respectively, in induced cardiomyocytes. Compared with the untreated control, PIP3 ELISA assay showed a significant increase in PIP3 levels in PIP3(10 nmol/L)-primed cardiomyocytes treated with 10 and 30 μmol/L of the 322PESB molecule derivative by 485.804 and 3564.164 ng/mL, respectively. In this study, we conducted the first promising molecular regulator with potential therapeutic implications for CTD patients. Further functional animal model and clinical phase studies are recommended.

Cardiomyocyte↗
PubMed1979

[Synthesis of (LysA13)bovine insulin A chain analogs as (Lys(Tfa)A13)A(SO3H)4 and Nalpha-A1-Msc-(LysA13)A(SO3H)4 derivatives using the S-tert-butylmercapto residue for thiol protection (author's transl)].

The following paper describes the synthesis of the [LysA13]bovine insulin A chain analog as [Lys(Tfa)A13]A(SO3H)4 and NalphaA1-Msc-[LysA13]A(SO3H)4 derivatives using the S-tert-butylmercapto residue for thiol protection. Although the intermediate S-tert-butylmercaptocysteinyl-peptide derivatives showed a good solubility in organic solvents the resulting fully protected A chain derivatives had a poor solubility in organic solvents and therefore were deblocked converted into the tetra(S-sulfonic acid) derivatives and purified via ionexchange chromatography.

Animals↗
PubMed1975

Motor-sensory cortex-corticospinal system and developing locomotion and placing in rats.

Normal and abnormal development of movement in the rat were studied by investigating the growth and organization of the motor-sensory cortexcorticospinal tract system (MSC-CST) and the functional and morphologic effects of ablating the MSC or quadrants of it at different ages. Major growth of the MSC outflow, the CST, in the brain stem and rostral cord occurred in the second and third weeks postnatally, coinciding approximately with the normal mid-week transition from infantile to mature locomotion. Ablation of the MSC at birth revealed that while the MSC-CST was not essential for ordinary locomotion on flat terrain, its presence hastened normal development of this kind of movement, and that it was absolutely essential for locomotion on difficult terrain. The MSC quadrants showed quite different, and in some domains mutually exclusive, CST projection patterns to forebrain, diencephalon, brain stem, and spinal destinations (determined by Fink-Heimer-Nauta fiber degeneration studies). Ablation of some quadrants produced distinctive syndromes of disordered movement: the posterolateral quadrant related to active grasping in positioning limbs, while the posteromedial quadrant related to tactile motor-sensory positioning of limbs. Thus in addition to the classic somatotopic organization of the MSC, there was another kind of organization into regions concerned with components of integrated movement of a number of parts of the body. Several forms of aberrant circuitry developed after MSC ablations in infants, but their possible roles in functional adaptation remain to be determined.

Age Factors↗
PubMed2024

Culture Expansion Alters Human Bone Marrow-Derived Mesenchymal Stem Cell Production of Osteoarthritis-Relevant Cytokines and Growth Factors.

PURPOSE: The purposes of this study were to characterize the human bone marrow-derived mesenchymal stem cells (BM-MSCs) production of osteoarthritis-relevant cytokines and growth factors as they are purified and multiplied, a process termed culture expansion, and to compare the immunomodulatory potential of BM-MSCs based on source and medium used for culture expansion. METHODS: BM-MSCs were obtained from iliac crest bone marrow aspirates of 4 healthy donors. These 4 BM-MSC cell lines underwent 4 rounds, or "passages," of the institutional culture expansion protocol, using institutional culture media. The secretory molecules known to play a role in osteoarthritis-related inflammatory immune response, cartilage degradation, and patient symptoms, together called the BM-MSC "secretome," were measured at each passage. Three lines of commercially available BM-MSCs from healthy donors underwent culture expansion by the same protocol, using commercial culture media. The commercial BM-MSCs secretome and the institutional BM-MSCs secretome were compared at each passage. Significance was set at P < .05. RESULTS: Institutional BM-MSCs produced less interleukin-6 at passages 3 (237 &#xb1; 113 pg/mL) and 4 (237 &#xb1; 113 pg/mL) compared with passages 1 (884 &#xb1; 97 pg/mL) and 2 (1071 &#xb1; 129 pg/mL; P < .01). Institutional BM-MSCs produced more macrophage inflammatory protein 3-alpha at passage 4 than at passage 1 (106 &#xb1; 41 vs 32 &#xb1; 7 pg/mL; P < .01). Across passages of culture expansion, institutional BM-MSCs grown on institutional medium expressed more interleukin-6 (P < .001), interleukin-10 (P < .001), interleukin-1 beta (P < .001), tumor necrosis factor alpha (P = .004), and vascular endothelial growth factor C (P = .003) than commercially available BM-MSCs grown on commercial medium. CONCLUSIONS: Culture expansion alters key molecules within the BM-MSC secretome. Additionally, differences in BM-MSC source and culture medium alter the BM-MSC secretome and its immunomodulatory potential. CLINICAL RELEVANCE: This study characterizes the in-vitro changes in BM-MSC secretome during culture expansion based on the cell source and culture medium. It suggests nonequivalence of culture-expanded BM-MSC therapies obtained from different donors using different culture media, even if delivering equivalent numbers of BM-MSCs.

Humans↗
PubMed2025

Inference of Gene Flow between Species from Genomic Data When the Mode, Direction, and Lineages are Misspecified.

Thanks to genomic data, interspecific gene flow is increasingly recognized as a major evolutionary force that shapes biodiversity. Two models have been developed in the multispecies coalescent (MSC) framework to infer gene flow from genomic data, assuming either constant-rate continuous migration (MSC-M) or discrete introgression/hybridization (MSC-I). The extreme simplicity of these models raises concerns about their usefulness as they represent misspecified models when applied to real data. Here, we study inference of gene flow under the MSC-M model, considering mis-assignment of gene flow onto incorrect parental or daughter lineages, misspecification of the direction of gene flow, and misspecification of the mode of gene flow. Mis-assignment of gene flow to an incorrect lineage causes large biases in the estimated rates. The Bayesian test has high power for inferring both recent and ancient gene flow, between either sister lineages or nonsister lineages, although misspecification of the direction of gene flow may make it hard to distinguish early divergence with gene flow from recent complete isolation. Misspecification of the mode of gene flow (MSC-I versus MSC-M) has small local effects, and gene flow is detected with high power despite the misspecification. We analyze a genomic dataset from the purple cone spruce (Picea spp., Pinaceae), which putatively arose through homoploid hybrid speciation, to demonstrate practical implications of our theoretical analyses. Overall, we find that the extremely idealized models of gene flow (in particular the discrete MSC-I model) are very effective for extracting information about species divergence and gene flow from genomic data.

Gene Flow↗
PubMed2026

Comparison of posterior cellular bonegraft options for single-level lumbar spinal fusion: a randomized trial.

BACKGROUND: Iliac bone autograft (IBG) is osteoinductive/osteogenic/osteoconductive but requires an additional harvesting procedure with known morbidities. Bone morphogenic protein (BMP) is osteoinductive and effective in obtaining fusion but is used off label for posterior fusion, has multiple side effects, and is expensive. Stem cell bone products, both auto- and allograft are attractive osteoinductive alternatives that avoid morbidity related to the graft donor site and may have a better safety profile than BMP. Morcelized allograft bone is osteoconductive but not osteoinductive or osteogenic. PURPOSE: Evaluate and compare the effectiveness of 6 types of viable or osteoinductive bone graft material in obtaining a solid posterior spinal fusion (PSF) for single level anterior/posterior lumbar spinal fusion. The bone grafts were IBG, BMP, autogenous stem cells (MSC) from concentrated bone marrow aspirate (BMA), allograft MSC from bone marrow, adipose tissue, or amniotic fluid, combined with inert cancellous allograft (Allo). STUDY DESIGN/SETTING: Prospective, single-blinded randomized study of 6 cohorts and inert historical control. PATIENT SAMPLE: Elective anterior-posterior lumbar spinal fusion of 175 patients. OUTCOME MEASURES: Assessments included pre and postoperative back and leg pain (VAS) scores, pain drawing, disability (ODI) scores, pain medication usage, and 1-year postoperative thin-cut CT scans (read by blinded radiologists). METHODS: Patients who were surgical candidates for a 1-level anterior/posterior lumbar fusion were randomized to 1 of 6 types of posterior bone graft alternatives: IBG, BMP, BMA, allograft MSC derived from bone marrow combined with morcelized Allo (cAlloBone), adipose derived MSC combined with morcelized Allo (cAlloFat), or amnion derived MSC combined with morcelized Allo (cAlloAm). Historical Allo patients served as a negative control group. Each group (n 27) had prospective outcomes and were followed for a minimum of 2 years. Fusion rate and outcomes were compared and referenced to Allo group. RESULTS: All but 5 patients had a solid ASF. The posterior fusion rates were 98% for IBG, 94% for BMP, 85% for BMA, 67% for cAlloBone, 64% for cAlloFat, 62% for cAlloAm, and 50% for Allo. Outcomes were significantly improved for all measures for all groups and there was no difference between groups except cAlloFat had slightly greater improvement in back pain in the 7-12 month follow-up period. BMP was the most expensive graft material; cellular allografts had a high-cost relative to fusion rate. CONCLUSIONS: For single level ASF/PSF, the PSF fusion rate was significantly greater for IBG and BMP followed by BMA. Various allograft MSC bone graft options resulted in lower fusion rates but may be greater than Allo. Outcomes were uniformly improved regardless of the type of graft used or the fusion status of the posterior fusion as long as the interbody fusion was solid. If bone graft cost savings is a consideration for PSF, then IBG has the greatest radiographic value, and Allo the greatest clinical value as long as the anterior interbody fusion is solid.

Humans↗
PubMed2025

Protective effect of ketamine and bone marrow-derived mesenchymal stem cell on ovarian follicular depletion i&#x307;n a rat i&#x307;schaemia/reperfusion model: An experimental study.

This study investigated the therapeutic potential of bone marrow-derived mesenchymal stem cells (BM-MSCs) and ketamine in alleviating ovarian ischemia-reperfusion (I/R) injury in a rat model. Forty-nine female rats were randomly divided into seven groups, each consisting of seven animals: Control, MSC (1&#x202f;&#xd7;10&#x2076; cells via tail vein), I/R, ketamine (10&#x202f;mg/kg, i.p.), I/R +&#x202f;ketamine, I/R +&#x202f;MSC, and I/R +&#x202f;ketamine +&#x202f;MSC. Biochemical analyses were performed using ELISA to measure malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), total antioxidant status (TAS), and total oxidant status (TOS). Histological evaluation included histopathological assessment and follicle counting, while the expression levels of TNF-&#x3b1;, IL-6, VEGF, and estradiol receptor (ER) were examined using immunohistochemical staining. Apoptotic cell counts were determined by the TUNEL method.I/R injury caused significant follicular degeneration, vascular congestion, edema, hemorrhage, and leukocyte infiltration, which were markedly improved by both MSC and ketamine treatments. The most pronounced improvement was observed in the MSC group. MSC therapy demonstrated strong anti-inflammatory effects by modulating TNF-&#x3b1; and IL-6, enhanced antioxidant defense by reducing MDA levels and increasing SOD and CAT activity. It exerted anti-apoptotic properties by decreasing the number of TUNEL-positive cells. In conclusion, BM-MSCs exhibited superior and longer-lasting protective effects compared to ketamine in repairing ovarian tissue damage induced by I/R injury and preserving fertility.

Animals↗
PubMed2025

Multicompartment Quantitative Proteomics Revealing Potential Mechanisms Underlying the Treatment Effects of Mesenchymal-Derived Extracellular Vesicles in a Monkey Model of Cortical Injury.

Previous studies have demonstrated that mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) enhance functional recovery after cortical injury in rhesus monkeys by reducing chronic microglial inflammation, neuronal damage, and myelination deficits. However, the signaling pathways underlying these therapeutic effects remain largely unexplored. In this study, employing a reliable quantitative proteomics platform UHR-IonStar, we identified the protein cargo of MSC-EVs infused intravenously to rhesus monkeys 24 h and 2 weeks post-injury to the motor cortex. We then analyzed global protein expression changes across cerebrospinal fluid (CSF), plasma, and brain tissue of MSC-EV-treated versus vehicle-treated female, aged rhesus monkeys. A total of 1241/431/4124 monkey proteins were reliably quantified in CSF/plasma/tissue samples, respectively. Longitudinal analysis of CSF and plasma samples highlighted a shift from MSC-EV modulation of inflammatory and metabolic proteins in plasma at early recovery (2 weeks), toward modulation of plasticity-related proteins in CSF and brain tissue at later stages (4 weeks). Further protein-protein interaction analysis identified potential MSC-EV targets related to complementary signaling, proteolysis, and aminoglycan stability, which aligned with our previous findings. This comprehensive, multicompartment monkey proteomics study advances understanding of MSC-EV contents and treatment effects, paving the way for novel treatment of cortical injury.

Animals↗
PubMedDate not supplied

Studies on isoprenaline-induced myocardial lesions. 1. Quantitative evaluation by mercurascan uptake.

For the quantitative evaluation of myocardial damage induced by isoprenaline (ISO) a method based on the uptake of 203Hg-labelled Mercurascan (MSC) in the heart was used. The increase of myocardial uptake of MSC in ISO-treated rats over control values was very rapid and might be directly proportional to the number of damaged myocardial cells actually present in the heart. MSC-uptake method of myocardial damage evaluation was more sensitive and precise than other methods tested (macroscopic evaluation according to Rona, increase of heart weight). Different modifications of MSC-uptake test may be selected in relation to experimental conditions. MSC test is especially useful for evaluation of early myocardial lesions induced by small doses of ISO (0.01 mg/kg).

Animals↗
PubMed1975

Postural changes in left ventricular and mitral valvular dynamics in the systolic click - late systolic murmur syndrome.

Marked changes in the auscultatory pattern with posture have been noted in patients with mid-systolic clicks and/or late systolic murmurs (MSC-LSM). MSC tend to move earlier in systole and LSM become longer and often louder when patients assume upright posture. Systolic prolapse of the mitral leaflets with mild regurgitation account for MSC-LSM; earlier and greater prolapse with more and prolonged regurgitation associated with a reduced left ventricular volume (LVV) in the upright position would explain the auscultatory changes. Twenty-two patients with MSC-LSM were studied supine and at 45 degrees head-up tilt, recording intracardiac pressures, cardiac outputs, systolic time intervals, and performing LV cineangiography. Systolic prolapse of one or both mitral leaflets was demonstrated in all patients. Left ventricular end-diastolic and end-systolic volumes both decreased significantly at 45 degrees in all sixteen technically satisfactory studies. Greater mitral prolapse was noted upright in 12 of 14 studies with enough sinus beats to judge. The amount of mitral regurgitation was mild in all, and changes in amount from supine to upright posture could not be discerned angiographically. THE FINDINGS, SUGGEST THAT THE AUSCULTATORY CHANGES OCCURRING WITH UPRIGHT POSTURE IN PATIENTS WITH MSC-LSM are related to greater prolapse of the mitral leaflets which is associated with a small LVV in the upright position.

Angiocardiography↗
PubMed1978

The effect of mercury derivatives of fluorescencein on allotransplant kidney in experiment.

Mercurascan (MSC), a mercury derivative of fluorescein, was studied as to its effect on the survival of allogeneic kidney grafts in dogs. A single perfusion of the donor's kidney with saline solution with MSC added in a ratio of 1 mg/100 ml was found to have significantly extended the graft survival time from 10.8 days (SE +/- 0.6) to 15.4 days (SE +/- 1.6). Graft survival time extension proved to be even more significant after a single dose of MSC given to the donor (0.5 mg/kg b.w.) and repeated administration of an equal MSC dose to the recipient twice weekly. Listed are detailed morphological changes in tissue specimens from the kidney, lymph nodes, spleen, and many other organs of a dog surviving for 42 days. A very moderate rejection lesion with merely tiny lymphocytic infiltrates was proved in the kidney. Lymph node structure was almost entirely obliterated with lymphoid tissue extinction. There was loss of white pulp in the spleen. The absence of morphological changes in the other organs suggested good tolerance of the preparation. More studies are called for to elucidate the complex MSC intervention in the process of rejection.

Animals↗
PubMed1978

Development and persistence of cytolytic T lymphocytes in regressing or progressing Moloney sarcomas.

Intratumoral T lymphocytes were recovered sequentially after induction of regressing or progressing Moloney sarcomas in BALB/c mice and were assayed quantitatively for their ability to kill specifically the tumor (MSC) cells used for induction. The cytolytic activities of the two lymphocyte populations described two distinct biphasic kinetic profiles that were similar in amplitude and duration but separated from each other by 4-6 days. In progressing neoplasm, there was a rapidly occuring accumulation of T lymphocytes highly cytolytic for MSC cells. This response, however, was not sustained and disappeared in association with the onset of unchecked tumor growth. In contrast, T lymphocyte cytolytic activity developed more slowly in regressing sarcomas and attained peak levels coincident with the beginning of tumor regression. Similar changes in cytolytic activity characterized T lymphocytes in lymph nodes draining tumors. When cultured in vitro for 4 days, non-cytotoxic T lymphocytes from regional lymph nodes draining progressing sarcomas regained very high levels of cytolytic activity. Such restitution was diminished, however, if MSC cell lysates, macrophages or macrophages fed MSC cell lysates were present during the culture period. These experiments provided presumptive evidence that T lymphocyte-mediated cytolytic activity was lost in progressively growing Moloney sarcomas as a consequence of suppression in vivo of the genesis and/or functional expression of cytolytic T lymphocytes, perhaps by macrophages and/or soluble tumor antigen.

Animals↗
PubMed1978

Detection of circulating tumor antigens in mice carrying a highly metastatic pulmonary squamous--cell carcinoma.

Recently we reported that the highly metastatic MSC-10 (mouse squamous carcinoma) is incapable of inducing transplantation immunity. Studies reported here were undertaken to determine whether or not the tumor is devoid of tumor-associated antigen. We found that sera from MSC-10 tumor-bearing mice contain soluble protein antigens which react with rabbit antisera made against the MSC-10 tumor, as demonstrated by immuno-diffusion. Such proteins were not detected in the sera of normal mice or mice bearing fibrosarcomas. A close temporal relationship was demonstrated between the appearance of circulating antigens and the occurrence of lung metastases. Protein components serologically indistinguishable from the circulating antigens were isolated from tumor cells. The molecular weight of these proteins is between 30,000 and 100,000 daltons. Studies with antisera to mouse leukemia virus showed that hte MSC-10 tumor antigens are not viral proteins. The lack of immunogenicity of this tumor for syngeneic hosts as well as its high metastatic activity may be due to the early appearance of soluble antigens in the circulation.

Animals↗
PubMed1979

Semisynthetic horse heart [65-homoserine]cytochrome c from three fragments.

Horse heart cytochrome c was treated with methylsulfonylethyloxycarbonyl succinimide (Msc-ONSu) to give fully N(epsilon)-protected cytochrome c. Treatment of this derivative with a hard base for 15 sec regenerated the native tetrahectapeptide chain. CNBr degradation of the protected compound produced three fragments bearing only protective Msc functions on epsilon-amino groups. The fragment comprising the sequence 81-104 was isolated from the mixture and acylated with N-hydroxysuccinimidyl-t-butyloxycarbonyl-L-methioninate. The resulting pentacosapeptide derivative was partially deprotected by treatment with acid and condensed in good yield (65%) with fully synthetic N(alpha66), N(epsilon72,73,79)- tetra-Msc-cytochrome-c-(66-79)-tetradecapeptide azide. This pathway is preferred because the pentadecapeptide azide derivative 66-80 acylated the N(epsilon)-protected tetracosapeptide sequence 81-104 in an unpredictable manner. Subsequent treatment of the product with a base produced unprotected semisynthetic cytochrome-c-(66-104)-nonatriacontapeptide, which is known to undergo acylation by unprotected [Hse(65)]cytochrome-c-(1-65)-pentahexacontapeptide lactone. The high specificity of this condensation is ascribed to "conformation direction." Semisynthetic [Hse(65)]cytochrome c thus prepared reacts like native cytochrome c with a succinate cytochrome c reductase preparation and with cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1). This semisynthetic strategy may provide a rapid route for the production of cytochrome c analogs modified in the highly conservative sequence 66-80.

Amino Acid Sequence↗