Effects of dissolved organic carbon on potentially toxic element desorption in stormwater bioretention systems

Stormwater runoff contains dissolved organic carbon (DOC) and potentially toxic elements (PTEs). Interactions between DOC and PTEs can impact PTE speciation and mobility, but are not fully understood. Soil samples were collected from a vegetated bioretention bed to investigate the effects of DOC (0, 15, and 50 mg-C/L) on the desorption of 10 PTEs captured by the soil media: Mn, Fe, Co, Cu, Zn, As, Cd, Sn, Sb, and Pb. In the absence of DOC, the desorbed PTE concentration from bioretention media into the aqueous phase ranking was as follows: Fe > Mn ∼ Zn > Cu > Pb > Sb > As > Co > Sn ∼ Cd. Increased DOC concentrations resulted in a reduction of the soil-water distribution coefficient (Kd) values. The greatest shift in Kd was observed for Cu and lowest for Sb. The PTE sorption capacities were lower for surficial soil samples (lower Kd) compared to the deep soil samples. Overall, the desorbed PTE (average midchannel 55.7 μg/g) fraction accounted for <1.1 % of the total extracted PTEs (5364 μg/g), and while this is a small percentage of the total, this is the fraction that is mobile. The extracted PTE fractions revealed that DOC reduced the organic matter-bound and carbonate-bound fractions. The PTE desorption trends suggest that reducing DOC in stormwater runoff could be an effective measure to mitigate the release of PTEs into the environment.

Quality-adjusted Time Without Symptoms of disease or Toxicity (Q-TWiST) analysis of CPX-351 versus 7 + 3 in older adults with newly diagnosed high-risk/secondary AML

BACKGROUND

CPX-351 (United States: Vyxeos^®; Europe: Vyxeos^® Liposomal), a dual-drug liposomal encapsulation of daunorubicin and cytarabine in a synergistic 1:5 molar ratio, is approved by the US FDA and the EMA for the treatment of adults with newly diagnosed therapy-related acute myeloid leukemia or acute myeloid leukemia with myelodysplasia-related changes. In a pivotal phase 3 study that evaluated 309 patients aged 60 to 75 years with newly diagnosed high-risk/secondary acute myeloid leukemia, CPX-351 significantly improved median overall survival versus conventional 7 + 3 chemotherapy (cytarabine continuous infusion for 7 days plus daunorubicin for 3 days), with a comparable safety profile. A Quality-adjusted Time Without Symptoms of disease or Toxicity (Q-TWiST) analysis of the phase 3 study was performed to compare survival quality between patients receiving CPX-351 versus conventional 7 + 3 after 5 years of follow-up.

METHODS

Patients were randomized 1:1 between December 20, 2012 and November 11, 2014 to receive induction with CPX-351 or 7 + 3. Survival time for each patient was partitioned into 3 health states: TOX (time with any grade 3 or 4 toxicity or prior to remission), TWiST (time in remission without relapse or grade 3 or 4 toxicity), and REL (time after relapse). Within each treatment arm, Q-TWiST was calculated by adding the mean time spent in each health state weighted by its respective quality-of-life, represented by health utility. The relative Q-TWiST gain, calculated as the difference in Q-TWiST between treatment arms divided by the mean survival of the 7 + 3 control arm, was determined in order to evaluate results in the context of other Q-TWiST analyses.

RESULTS

The relative Q-TWiST gain with CPX-351 versus 7 + 3 was 53.6% in the base case scenario and 39.8% among responding patients. Across various sensitivity analyses, the relative Q-TWiST gains for CPX-351 ranged from 48.0 to 57.6%, remaining well above the standard clinically important difference threshold of 15% for oncology.

CONCLUSIONS

This post hoc analysis demonstrates that CPX-351 improved quality-adjusted survival, further supporting the clinical benefit in patients with newly diagnosed high-risk/secondary acute myeloid leukemia. Trial registration This trial was registered on September 28, 2012 at www.clinicaltrials.gov as NCT01696084 ( https://clinicaltrials.gov/ct2/show/NCT01696084 ) and is complete.

Long-term simulation of potentially toxic elements (PTEs) accumulation and breakthrough in infiltration-based stormwater management practices (SMPs)

Stormwater management practices (SMPs) rely on infiltration and adsorption capabilities of soil and vegetative cover to mitigate the harmful impacts of contaminants in stormwater runoff, including potentially toxic elements (PTEs). Under chemical equilibrium conditions, the soil-water distribution coefficient (K_d) quantifies the relationship between the solid and aqueous phase PTE concentrations, and thus the PTE removal efficiency and mobility through the SMP soil layers during the infiltration process. The SMP loading ratio (LR), the ratio of the drainage area to the SMP infiltration area, combined with runoff concentration determines SMP mass loading and is also expected to impact PTE transport. In this study, a simulation model was developed to investigate PTE breakthrough and build-up in SMP media, considering the impacts of K_d and LR. Eight PTEs were simulated (Cl^-, Cr, Fe, Zn, Cu, As, Cd, and Pb), and Cl^- was the only PTE that showed high mobility and reached the groundwater table (e.g., ~ 1 year for breakthrough). Conversely, other PTEs were effectively immobilized in the top ~60 cm of soil for a simulated lifespan of 20 years. Soil and porewater contaminant indices, as indicators of SMP lifespan, were estimated based on the ratio of PTE porewater and soil concentrations after 20 years to published standards, suggesting the following order of environmental significance (most concern to least): Cl^- > Cr > As > Pb > Fe > Cu > Cd > Zn. After 20 years of simulated use, only Cl^- pore water concentrations at the groundwater table exceeded regulatory values, with porewater contamination index values of 4 to 7.5. Chloride also exceeded the surficial media soil contamination index, as did As and Cr, though these exceedences were largely associated with media background concentrations. Generally, higher LR and K_d contributed to higher accumulation of PTEs in top layers; however, simulations showed that the combination of low LR and high K_d may result in lower PTE accumulation in the media, such that the PTE concentration in soil may decrease in deeper layers. In these scenarios, a notable fraction of PTE load was adsorbed on top layers and considerably lower PTE concentrations reached the lower layers. Sensitivity analysis revealed that dispersion, infiltration rate, and kinetically-limited sorption did not impact the PTE accumulation and mobility to a practical extent. The results from this simulation may be adapted to various environmental conditions to enhance the design and maintenance of SMPs.

Healthcare resource utilization in a phase 3 study of CPX-351 in patients with newly diagnosed high-risk/secondary acute myeloid leukemia

Aims: Treatment of acute myeloid leukemia (AML) requires significant healthcare resource utilization (HRU), including lengthy hospitalizations. In a phase 3 study (NCT01696084), CPX-351 (Vyxeos) showed significant benefits to overall survival and complete remission versus conventional 7 + 3 cytarabine/daunorubicin. This analysis evaluated HRU in patients aged 60-75 years with newly diagnosed high-risk/secondary AML treated with CPX-351 versus 7 + 3 in the phase 3 study.Materials and methods: Patients were randomized to receive up to two induction cycles with CPX-351 or 7 + 3. Responders could receive up to two cycles of consolidation. To normalize HRU to length of treatment, patients were assessed on a per patient-year (PPY) basis. HRU analyses included hospital and intensive care unit (ICU) stays, anti-infective use, transfusions, and white blood cell colony-stimulating factor (CSF).Results: The median (range) total duration of hospitalization was 39 (3-110) days with CPX-351 (n = 153) and 32 (2-83) days with 7 + 3 (n = 151); the estimated durations of hospitalization PPY were 198.4 and 240.5 days, respectively. The median (range) total duration of ICU stays was 0 (0-45) days with CPX-351 and 0 (0-17) days with 7 + 3; the estimated durations of ICU stays PPY were 6.7 and 10.5 days, respectively. When comparing supportive care use during CPX-351 and 7 + 3 treatment, the estimated number PPY of bags of platelets used (24.6 vs 26.9, respectively), bags of packed red blood cells used (13.0 vs 13.9), days of anti-infectives (162.0 vs 159.2), and days of CSF (4.0 vs 2.4) were not notably different.Limitations: This clinical study analysis may not represent real-world HRU patterns or be generalizable to a broader AML population.Conclusions: These PPY data, showing shorter durations of hospitalization and similar use of supportive care with CPX-351 versus 7 + 3, suggest CPX-351 is not associated with increased HRU in older patients with newly diagnosed high-risk/secondary AML.

Outcomes in older patients with high-risk/secondary AML who achieved remission with CPX-351 versus 7+3 but did not undergo transplant: Phase 3 exploratory analysis

7537

Background: CPX-351 (Vyxeos; daunorubicin [D] and cytarabine [C] liposome for injection) is approved by the FDA and EMA for the treatment of adults with newly diagnosed therapy-related AML or AML with myelodysplasia-related changes. In a phase 3 study (NCT01696084) in patients (pts) aged 60-75 y with newly diagnosed high-risk/secondary AML, CPX-351 demonstrated significantly longer overall survival (OS) and higher rates of remission and hematopoietic cell transplant (HCT) vs conventional 7+3, with a comparable safety profile. To better understand the impact of treatment on outcomes in pts who did not undergo HCT, this exploratory analysis evaluated outcomes in the subgroup who achieved complete remission (CR) or CR with incomplete neutrophil or platelet recovery (CRi) with CPX-351 vs 7+3 but did not undergo HCT. Methods: Pts were randomized 1:1 to receive ≤2 induction cycles of CPX-351 (100 units/m2 [C 100 mg/m2 + D 44 mg/m2] as a 90-min infusion on Days 1, 3, 5 [2nd induction: Days 1, 3]) or 7+3 (C 100 mg/m2/d continuously for 7 d + D 60 mg/m2 on Days 1-3 [2nd induction: 5+2]). Pts achieving CR or CRi could receive up to 2 consolidation cycles. Pts could receive HCT at the physician’s discretion. Results: CR+CRi was achieved by 73/153 (48%) pts with CPX-351 vs 52/156 (33%) with 7+3; of these pts, 33/73 (45%) vs 28/52 (54%) did not subsequently undergo HCT. The baseline characteristics of these pts were generally balanced between arms; however, the CPX-351 arm had more male pts vs 7+3 (64% vs 43%) and pts with ECOG PS of 1 (82% vs 54%), and fewer pts with antecedent MDS and HMA exposure (21% vs 39%). Median OS was longer with CPX-351 vs 7+3 (14.72 vs 7.59 mo; HR = 0.57 [95% CI: 0.31-1.03]; Table). There was no early mortality by Day 60 in either arm (see Table for additional data). Conclusions: CPX-351 improved median OS vs 7+3 in pts who achieved CR+CRi but did not undergo HCT, suggesting a treatment benefit with CPX-351 even among pts who do not undergo HCT. The CPX-351 safety profile in this subgroup was consistent with the overall study population and known profile of 7+3. Clinical trial information: NCT01696084 . [Table: see text]

Pooled analysis of Day 100 survival for defibrotide-treated patients with hepatic veno-occlusive disease/sinusoidal obstruction syndrome and ventilator or dialysis dependence following haematopoietic cell transplantation

For patients with untreated hepatic veno-occlusive disease (VOD)/sinusoidal obstruction syndrome (SOS) with multi-organ dysfunction (MOD), mortality is >80%. We conducted a pooled analysis of three studies that assessed Day 100 survival in relationship to MOD severity, with dialysis and/or ventilator dependence representing the most severe organ dysfunction. All patients in the analysis were diagnosed using Baltimore criteria/biopsy. This analysis of patients with VOD/SOS and MOD after haematopoietic cell transplantation (HCT; n = 651) demonstrated higher Day 100 survival rates amongst defibrotide-treated patients with VOD/SOS with less versus more severe forms of MOD. Even patients with severe forms of MOD post-HCT benefitted from defibrotide.

Outcomes with CPX-351 versus 7+3 by baseline bone marrow (BM) blast percentage in older adults with newly diagnosed high-risk/secondary acute myeloid leukemia (sAML)

7042

Background: CPX-351, a liposomal encapsulation of cytarabine (C) and daunorubicin (D) at a synergistic ratio, is approved as Vyxeos in the US and EU for adults with newly diagnosed therapy-related AML or AML with myelodysplasia-related changes. In a phase 3 study, CPX-351 significantly improved OS and remission rates vs 7+3 in patients (pts) aged 60-75 y with newly diagnosed high-risk/sAML. Some studies suggest a high baseline blast percentage may portend a worse prognosis in AML. This post hoc analysis of phase 3 data assessed outcomes by baseline BM blast percentage. Methods: Pts diagnosed with AML per 2008 WHO criteria (≥20% blasts in peripheral blood or BM) were randomized 1:1 to receive ≤2 inductions of CPX-351 (100 units/m2 [C 100 mg/m2 + D 44 mg/m2] on Days 1, 3, 5 [2nd induction: Days 1, 3]) or 7+3 (C 100 mg/m2/d continuously for 7 d [2nd induction: 5 d] + D 60 mg/m2 on Days 1-3 [2nd induction: Days 1-2]). Pts achieving complete remission (CR) or CR with incomplete platelet or neutrophil recovery (CRi) could receive ≤2 consolidations. Results: CPX-351 had longer median OS and higher remission rates vs 7+3 irrespective of baseline BM blast percentage; median OS was worse in higher blast groups for both treatments (Table). The incidence of grade ≥3 TEAEs was >80% for both arms; febrile neutropenia was the most common. Conclusions: Improved outcomes were observed with CPX-351 vs 7+3 irrespective of baseline BM blast percentage in older adults with newly diagnosed high-risk/sAML. Clinical trial information: NCT01696084. [Table: see text]

Lateral and longitudinal variation of hyporheic exchange in a piedmont stream pool

A conservative solute tracer experiment was conducted in Indian Creek, a small urban stream in Philadelphia, PA, to investigate the role of subsurface properties on the exchange between streamwater and the hyporheic zone (subsurface surrounding the stream). Sodium bromide (NaBr) was used as a conservative tracer, and it was monitored in the surface water and in the bed sediments of a 15 m long pool. Subsurface sampling occurred at 12 locations in the upper layer sediments (extending from 7.5 to 10 cm below the streambed) and 13 locations in the lower layer sediments (extending from 10 to 12.5 cm below the streambed). The hydraulic conductivity (K) of the upper bed sediments and the lower bed sediments was measured in situ. Several locations within the streambed exhibited an increase in tracer concentration with depth, suggesting the presence of horizontal flow paths within this small pool. Over the entire pool, the influence of K heterogeneity on hyporheic exchange was masked by the groundwater head gradient and the morphology of the stream. Together, the groundwater head gradient and stream morphology induced a generally high tracer concentration and fast hyporheic exchange on the left side and center of the channel and low concentrations and slower exchange on the right side. Although the reach-scale effects on the surface water concentration were small, groundwater greatly influenced the local-scale hyporheic exchange in the pool. Understanding how physical stream characteristics control the location and extent of hyporheic exchange pathways will lead to a better understanding of biogeochemical cycling of nutrients and contaminants.

Incomplete mixing in a small, urban stream

Conservative solute tracer experiments were conducted in Indian Creek, a small urban stream located in Philadelphia, Pennsylvania, USA. Estimated flow rates were between 46 Ls(-1) and 81 Ls(-1), average stream width was 5.5m and average stream depth was 0.2m. Given these dimensions, most researchers would think it reasonable to assume that the stream is completely mixed vertically and horizontally. However, we found that the stream was not vertically completely mixed in a 1.0m deep, 30 m long pool. The limited mixing was demonstrated by the vertical stratification of a tracer cloud which was completely mixed both laterally and vertically across the stream prior to entering the pool. We suggest that the cause of limited mixing is due to a balance between groundwater inflow and transverse dispersion at the cross-section. We show that the unsupported assumption of complete mixing may result in a wide range, and thus increased uncertainty, of the values of stream flow and longitudinal dispersion coefficient estimated from these data. We conclude that the assumption of complete mixing and one-dimensional modeling must be checked against actual field conditions, even in small streams.

Identification of hormone-binding regions of the luteinizing hormone/human chorionic gonadotropin receptor using synthetic peptides

A comprehensive series of overlapping synthetic peptides have been used to study the relationship between the primary structure of the ovarian receptor for LH/human CG (hCG) and hormone binding. Twenty-four consecutive, overlap peptides that replicate the entire extracellular domain of the rat luteal receptor have been synthesized by standard solid-phase techniques on an automated synthesizer. Eight additional peptides from the extracellular domain and three peptides replicating the putative extracellular loop regions have also been synthesized. Each peptide was evaluated in RRAs for interaction with hCG by measuring its ability to competitively inhibit binding of 125I-hCG to membrane receptor. Twelve peptides were found to be potent in RRAs and caused a reduction of half-maximal binding of 125I-hCG at concentrations of 10-250 x 10(-6) M. The 12 active peptides (and adjacent inactive peptides) defined at least 4 independent receptor regions that can interact with hormone. One site near the NH2-terminus was localized to receptor residues Arg21-Pro38. Two more sites of hormone interaction were identified by peptides replicating residues Arg102-Thr115 and Tyr253-Phe272. A fourth binding region was identified in the third putative extracellular loop, replicated by rat luteal receptor peptide Lys573-Lys583. The amino acid sequences of the four active rat LH/hCG receptor regions were aligned and compared with published sequences for other glycoprotein hormone receptors. Three regions (Arg102-Thr115, Tyr253-Phe272, and Lys573-Lys583) showed high sequence homology with the human LH/hCG receptor, human TSH receptor, and rat FSH receptor and may represent contact sites for the alpha-subunit of hormone. The other binding region, Arg21-Pro38 had low sequence homology with the other glycoprotein hormone receptors and is postulated to be a binding determinant for beta-hCG/LH. This report demonstrates that synthetic overlap peptides of confirmed sequence can be used to successively identify hormone interaction sites of glycoprotein hormone receptors.

The identification of spinal pathology in chronic low back pain using single photon emission computed tomography

Bone scintigraphy with single photon emission computed tomography (SPECT) offers improved lesion detection and localization when compared to conventional planar imaging. The SPECT findings were investigated in 80 consecutive patients (aged 18-70 years, median 44) referred to a rheumatology outpatient clinic with low back pain persisting for more than 3 months. Lesions of the lumbar spine were demonstrated in 60% of patients using SPECT but in only 35% with planar imaging. Fifty-one per cent of all lesions were only detected by SPECT, and lesions visualized on SPECT could be precisely localized to the vertebral body, or different parts of the posterior elements. Fifty per cent of lesions involved the facetal joints of which almost 60% were identified on SPECT alone. X-rays of the lumbar spine, with posterior oblique views, failed to demonstrate abnormalities corresponding to almost all SPECT posterior element lesions although it identified abnormalities corresponding to over 60% of anterior SPECT lesions. Computed tomography (CT) was performed in 30 patients with a SPECT lesion and sites of facetal joint activity corresponded to facetal osteoarthritis in 82%. It is concluded that bone scintigraphy with SPECT in patients with chronic low back pain demonstrates many lesions not seen with either X-ray or conventional planar imaging. In addition anatomical localization is greatly enhanced with bone SPECT. The technique offers improved diagnosis in a group of patients often difficult to evaluate, and in particular a means of detecting apophyseal joint pathology which may be responsive to treatment.

Inhibition of TSH bio-activity by synthetic beta TSH peptides

The in vitro bioactivity of the human beta TSH subunit was investigated utilizing eleven overlapping synthetic peptides representing the entire 112 residue sequence. The peptides were tested for both stimulatory and inhibitory activity in two sensitive bioassay systems: the first based on cAMP production in FRTL-5 rat thyroid cells, and the second based on stimulation of iodine trapping by the same continuous cell line. Peptides from three distinct regions of the beta-subunit showed concentration dependent inhibition of TSH bio-activity, including beta 1-15, beta 11-25, beta 31-45, beta 81-95, and beta 91-105 with IC50 values ranging from 150 to 304 microM. An additional peptide representing the entire sequence of the "intercysteine loop" region of beta TSH, beta 31-52, also inhibited TSH activity with somewhat higher potency than its fragment peptide beta 31-45 (IC50 of 87.5 +/- 14.7 microM for beta 31-52 versus 207 +/- 92.4 microM for beta 31-45). Three of these, beta 1-15, beta 31-45, and beta 31-52, also inhibited binding of TSH to the receptor in a radio-receptor assay, as previously reported (1), supporting their importance in receptor interaction. None of the synthetic peptides stimulated either cAMP production or iodine trapping. Two other overlapping peptides, beta 81-95 and beta 91-105, possessed bio-inhibitory activity but did not inhibit binding of labeled TSH. Computer analysis of this sequence predicted an extended turn structure for this region. This region has been referred to as the "determinant loop" as it is bounded by cysteine residues at positions 88 and 95 that many believe form a disulfide bond in the native subunit. The current data suggests the beta 88-95 region may play a role in receptor activation after initial binding of hormone to receptor.

Further characterization of the receptor-binding region of the thyroid-stimulating hormone alpha subunit: a comprehensive synthetic peptide study of the alpha-subunit 26-46 sequence

Previously, using a synthetic peptide strategy, we determined that the region of the common glycoprotein hormone alpha subunit between residues 26 and 46 is a site of interaction of the hormone with the thyroid membrane-bound receptor for thyroid-stimulating hormone (TSH). We have undertaken to identify further the specific residues within this 21-amino acid span that are critical in hormone receptor binding. We synthesized three nested sets of peptide, two in which we systematically truncated the amino-terminal region of the sequence and another in which we truncated the carboxyl-terminal region, and we synthesized a fourth nested set in which we systematically substituted alanine for the native residues from the region of highest activity. Each peptide was tested in a TSH radioreceptor assay for its ability to inhibit binding of 125I-labeled bovine TSH to porcine thyroid membranes. Removal either by truncation or alanine substitution, of several specific residues resulted in a significant reduction in the ability of the sequence to interact with receptor; these residues included Cys31, Cys32, Phe33, Arg35, Arg42, Lys44, and Lys45, suggesting that they are crucial for binding activity. Loss of activity also occurred with substitution for Gly30 and Ser34, but the reduction was less pronounced. Amino-terminal truncation of the sequence through Arg35 (leaving the alpha-subunit peptide 36-46) resulted in greater than 98% loss of activity of the sequence. We conclude that two distinct receptor binding regions lie within the alpha-subunit 26-46 sequence. The first lies between residues Gly30 and Arg35 and includes Cys31, Cys32, and Phe33 as important constituents, and the second region lies between residues Arg42 and Lys45 and includes Lys44 as an important residue and Ser43 as a less important component.

Residues in the alpha subunit of human choriotropin that are important for interaction with the lutropin receptor

Synthetic peptides were used to probe the structure-function relationships between human choriotropin (hCG) and the lutropin (LH) receptor. Previously, a peptide region of the alpha subunit of hCG, residues 26-46, had been shown to inhibit binding of 125I-hCG to the LH receptor in rat ovarian membranes (Charlesworth, M.C., McCormick, D.J., Madden, B., and Ryan, R.J. (1987) J. Biol. Chem. 262, 13409-13416). To determine which residues are important for this inhibitory activity, peptides were truncated from either the amino or carboxyl terminus, or individual residues were substituted with alanine. The amino-terminal boundary was determined to be Gly-30 and the carboxyl-terminal boundary, Lys-44. This core peptide contained all the residues needed for full activity of the parent peptide 26-46. Arg-35 and Phe-33 were particularly important residues; when they were substituted with alanine, the peptide inhibitory potencies were decreased. Ser-43, Arg-42, Cys-32, and Cys-31 were also important but to a lesser degree. These results are consistent with predictions based on chemical and enzymatic modification studies and provide insight into which residues are important for interaction between hCG and the LH receptor.

The antigenic structure of the human glycoprotein hormone alpha-subunit: III. Solution- and solid-phase mapping using synthetic peptides

Twenty-seven synthetic peptides, representing the entire structure of the human glycoprotein hormone alpha-subunit were used to map the antigenic structure of the alpha-subunit. Solution phase and solid phase assays were performed with these peptides and a panel of eight monoclonal antibodies (MAb). Two dominant regions were localized between residues 22-37 and 70-87. All eight antibodies recognized these regions, but differed somewhat with respect to whether they saw the more N-terminal, middle, or C-terminal portions of these regions. The sequence of residues 13-22 was recognized by three MAbs. The C-terminal region from residues 84-92 was recognized by three MAbs. All MAbs recognized conformational epitopes in that they reacted with two or more regions. Three MAbs (two against free alpha and one against human CG) have linear amino acid sequences as part of their conformational epitope.

The antigenic structure of the human glycoprotein hormone alpha-subunit. I. Characterization of anti-alpha monoclonal antibodies

The glycoprotein hormones CG, LH, FSH, and TSH are composed of two noncovalently linked subunits, alpha and beta. The beta-subunit confers hormone specificity, while the alpha-subunit is homologous within a species. To help in determining the antigenic structure of the common alpha-subunit, six monoclonal antibodies (mAbs) to the free or heterodimeric alpha-subunit of human (h) gonadotropic hormones have been prepared and, along with two previously isolated mAbs, have been characterized for binding specificity to alpha- and beta-subunits and the human glycoprotein hormones, CG, LH, FSH, and TSH. Each mAb was derived from hybidomas of FO myeloma cells fused with spleen cells from mice immunized with free alpha-subunit, hCG or hFSH. mAbs A101, A102, and E512 were specific for the alpha-subunit but showed the highest affinity for the intact hormone; K2.18, K94.6, E501, E502, and E511 were specific for free alpha. All of the antibodies inhibited binding of 125I-hCG to luteal membrane receptor, and 125I-labeled mAbs did not recognize hCG/receptor complex. Characterization by two-site binding assays using alpha, hCG, or hFSH as antigen revealed that all the mAbs bind to unique sites on alpha which may be overlapping, and which are modified in the intact hormone. The antigenic sites for mAbs E502, E511, and K2.18 are at least partially linear because they bind to reduced, carboxymethylated alpha.

The antigenic structure of the human glycoprotein hormone alpha-subunit: II. Cross-species comparisons

Eight monoclonal antibodies, specific for the glycoprotein hormone alpha-subunit, were raised against human free alpha-subunit, human FSH, or human CG. All of these antihuman monoclonal antibodies were tested for cross-reactivity with alpha-subunits derived from bovine, porcine, equine, bull frog, sea turtle, turkey, and ostrich glycoprotein hormones. All showed cross-reactivity with affinities ranging from 10(-4) to 10(-8) depending upon the antibody and the species of alpha-subunit. Cyanogen bromide fragments of bovine and equine alpha, when tested with selected antibodies indicated that antigenic determinants could be localized in two regions: alpha 9-33 and alpha 76-92. Comparison of amino acid sequences, and relative potencies, suggest that major antigenic determinants involve residues 21, 22, and 23 (F-F-S in human alpha) and 76-85 (G-G-F-K-V-E-N-H-T-A in human alpha). As part of this study the N-terminal amino acid sequences of bull frog, sea turtle, turkey, and ostrich alpha-subunits were determined and reported for the first time.

Molecular modeling of residues 38-57 of the beta-subunit of human lutropin

Several regions on both the alpha- and beta-subunits of human LH comprise the receptor-binding domain of the hormone. One of these, a disulfide loop peptide containing residues 38-57 on the beta-subunit, also stimulated steroidogenesis in rat Leydig cells. Circular dichroism analysis and a Schiffer-Edmundson helical wheel projection of beta-(38-57) revealed the possibility of an amphipathic alpha-helical structure through its N-terminal region. Secondary structure prediction algorithms do not predict alpha-helix in beta-(38-57), but, rather, suggest a sheet-coil-sheet topology. Homology searches between this peptide and proteins with known structure revealed that the two best matches are with prealbumin-(10-30) and melittin-(1-26). Based on hydrophobic moment calculations, we suggest that beta-(38-57) more closely resembles melittin, a known example of an amphipathic helix. Molecular models were constructed that included an alpha-helix between Pro-39 and Pro-50 producing a hydrophilic face involving Thr-40, Arg-43, and Gin-46. Loop closure was performed either visually or by an incremental minimization procedure, using distance constraints to patch in a disulfide bond. Molecular dynamics at 300, 360, and 1000 K were used to explore the local conformational space, and dynamic structures were minimized. The most reasonable structures were found with the 300 and 360 K simulations, with those at 360 K consistently producing structures with lower conformational energies. In each of these simulations, the N-terminus of the alpha-helix unraveled to form a reverse turn (predicted by the GOR algorithm) which include Cys-38, Pro-39, Thr-40, and Met-41. Simulations at 1000 K produced the most variation in structure, but these were deemed unreasonable. Although not all possible conformations were explored, several models were found that comply with the assumption of an amphipathic helix in the N-terminal half of the peptide.

Synthetic alpha-subunit peptides stimulate testosterone production in vitro by rat Leydig cells

The glycoprotein hormones (LH, hCG, FSH, and TSH) have a common 92-amino acid alpha-subunit which is noncovalently linked to a hormone-specific beta-subunit. Synthetic peptides of the alpha-subunit have been shown to inhibit binding of [125I]iodo-hCG to rat ovarian membrane and [125I]iodo-TSH to human thyroid membrane preparations. Synthetic overlapping peptides of the alpha-subunit of hCG were prepared by solid phase techniques and tested in a standard in vitro rat Leydig cell bioassay. Three regions in the alpha-subunit (alpha 1-15, alpha 30-45, and alpha 71-85) were found to stimulate testosterone production. All three regions correlate with inhibition of hCG binding to ovarian receptors, but subtle differences exist between the binding sites and effector sites. These data indicate that the glycoprotein alpha-subunit has intrinsic bioactivity.

Inhibition of thyrotropin binding to receptor by synthetic human thyrotropin beta peptides

In order to study the structure and function relationships of the thyrotropin (TSH)-specific beta-subunit, we produced 11 synthetic overlapping peptides containing the entire 112-amino acid sequence of human beta TSH and tested them for activity in TSH radioreceptor assay using both human and porcine thyroid membranes. Synthetic peptides representing four regions of the beta-subunit demonstrated the ability to inhibit binding of 125I-bovine TSH to crude thyroid membranes. The peptide representing the -COOH terminus of the subunit (beta 101-112) possessed highest binding activity, inhibiting binding of labeled TSH with an EC50 of 80 microM. The remaining active peptides were: beta 71-85 (104 microM), beta 31-45 (186 microM), beta 41-55 (242 microM), and beta 1-15 (331 microM). Specificity of the binding activity was shown by the inability of the peptides representing the remainder of the subunit to inhibit binding of label and by the inability of any of the peptides to inhibit binding of 125I-epidermal growth factor to the same thyroid membranes. The low affinity of the peptides as compared with native hormone is in agreement with previous studies of synthetic alpha-subunit peptides and, further, suggests that the interaction of beta TSH with receptor is multifaceted, requiring cooperative binding of these sites for the observed high affinity of the whole hormone. These studies are in agreement with previous predictions of active regions by chemical modification but add two regions to the list, showing the utility of the synthetic peptide strategy in the study of peptide hormone structure-activity relationships.

Synthetic peptide segments of inhibin alpha- and beta-subunits: preparation and characterization of polyclonal antibodies

The amino acid sequences of human inhibin alpha-, beta A- and beta B-subunits were analyzed for hydrophilicity and chain flexibility to predict regions that are on the surface of the subunits and, therefore, are potential antigenic sites. Based on these analyses, a total of nine peptides were synthesized, and rabbit antisera against the peptides were prepared. Peptides of the N-terminus (residues 1-16 and 13-24) and region 109-123 of the alpha-subunit produced high titer antibodies. Regions 69-79 and 93-105 of the beta A-subunit and region 93-104 of the beta B-subunit were also immunogenic. Immunoblotting of an inhibin preparation with anti-alpha-peptide antiserum revealed that a 32K band (inhibin) and an 18K band (alpha-subunit) were stained. Immunoblotting with anti-beta-peptide antiserum detected a 32K band (inhibin), a 24K band (activin), and a 14K band (beta-subunit). Injection (iv) of these antisera into rats induced dramatic elevation of serum FSH in 6-12 h and suggested immunoneutralization of endogenous inhibin. RIAs for each subunit were developed using radioiodinated peptides as tracers. Competition binding assays indicated crossreactivity with human follicular fluid, semen, serum, plasma, and crude inhibin preparations. Parallel dilution curves were obtained. Antisera against beta A- and beta B-subunit peptide cross-reacted with each other. In immunocytochemical studies, these antisera were used in conjunction with gold-labeled goat antirabbit immunoglobulin G to localize inhibin in cells of the rat testis. Specific staining of inhibin was localized within the Sertoli cells of some tubules in adult rat testis. Positive staining could be blocked by preadsorbing the sera with the appropriate synthetic peptide. These results suggest that antibodies against synthetic inhibin peptides are useful in elucidating the roles of inhibin and activin.

Purification, characterization, and amino-terminal sequence of rat ovarian receptor for luteinizing hormone/human choriogonadotropin

The luteinizing hormone (LH)/human choriogonadotropin (hCG) receptor of rat ovary was solubilized with Lubrol PX in the presence of 20% glycerol and protease inhibitors, and purified by one-step affinity chromatography. Purified receptor had a specific hCG binding capacity of 4900 pmol/mg protein, and displayed a single class of high affinity binding sites (Ka = 6.20 X 10(9) M-1). An 11,200-fold purification over the starting crude homogenate was achieved. The purified LH/hCG receptor was identified by sodium dodecyl sulfate-gel electrophoresis and silver staining as a single protein of 92 kDa. The ability of the purified 92-kDa protein to specifically bind hormone was demonstrated by electroblotting onto Immobilon P membrane, incubation with 125I-labeled hCG, and autoradiography of the blot. In addition to a 92-kDa band, ligand blotting also yielded a 170-kDa band representing receptor dimer. Covalent cross-linking of hCG, with isotope in either the alpha- or beta-subunit, to membrane-bound receptor produced complexes that contained a single receptor component of approximately 92 kDa. The cross-linking studies indicated that both subunits interact with receptor and also suggested receptor dimer formation. Following sodium dodecyl sulfate-electrophoresis, purified receptor was electroblotted onto polyethylenimine-treated glass fiber filters for direct microsequencing in a gas-phase sequenator. Eleven cycles of sequence analysis yielded the unique sequence: NH2-Arg-Glu-Leu-Ser-Gly-Ser-Leu-XXX-Pro-Glu-Pro-COOH. These results indicate that the rat ovarian LH/hCG receptor is a protein of 92 kDa which can be easily purified in microgram amounts. This study also describes a relatively simple technique for electroblotting and microsequencing that should be applicable to other membrane-bound hormone receptors.

Role of the beta 93-100 determinant loop sequence in receptor binding and biological activity of human luteinizing hormone and chorionic gonadotropin

The intercysteine loop sequence (93-100) in the beta-subunit has been postulated to be important for receptor binding and specificity in the glycoprotein hormones, LH and human CG (hCG). To demonstrate this directly, and to characterize the structural features essential for activity, we prepared a series of synthetic peptides and analogs incorporating this determinant loop region. Peptides were assayed for inhibition of labeled hCG binding to ovarian membrane receptors and stimulation of testosterone production in Leydig cells. Peptides with the native (93-100) sequence from hCG and hLH inhibited hCG binding half maximally at 2.18 and 2.62 x 10(-4) M, respectively, while the sequence from FSH was inactive. Isosteric substitution of Ala for Cys resulted in an inactive peptide, indicating that the (93-100) disulfide bridge is essential for activity. Optimal binding activity requires at least one net positive charge among the side chains, as shown by loss of activity in hybrid analogs with neutral or negative charges conferred by progressive replacement of Arg by Asp at 94 and 95 or by introduction of Asp at 96 and 97. Despite binding to receptors, the native sequence did not promote testosterone production at doses up to 10(-2) M. This contrasts with a second receptor binding sequence, beta (38-57) that activates testosterone production. There are differences between the (93-100) and (38-57) loop sequences in their chemical and physical properties, biological activity and antigenicity. While the cumulative evidence suggests that they associate with counterpart sites in alpha-subunit to form a topographical binding domain in the whole hormone, our results suggest that each sequence may contribute in different ways to activation of postreceptor events.

Primary and secondary structural determinants in the receptor binding sequence beta-(38-57) from human luteinizing hormone

The intercysteine "loop" sequence 38-57 in the beta subunit has been shown to be a determinant for expression of biological activity in human lutropin (hLH) and choriogonadotropin (hCG) [Keutmann, H. T., Charlesworth, M. C., Mason, K. A., Ostrea, T., Johnson, L., & Ryan, R. J. (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 2038]. Together with other sequences, the 38-57 region may contribute to a multicomponent receptor binding domain in hLH/hCG. Because the structural features influencing activity in this important region are not easy to evaluate in the full-length subunit, we have used analogues of hLH beta-(38-57) prepared by solid-phase synthesis. The peptides were tested for inhibition of 125I-labeled hCG binding to rat ovarian membrane receptors. Secondary structure was analyzed by circular dichroism (CD) and by reactivity with antibodies to the native 38-57 peptide. An analogue lacking the 38-57 disulfide linkage retained 20% receptor binding and full immunoreactivity. "Far"-ultraviolet CD profiles were essentially identical with those of the disulfide-intact peptide; a transition from 10% to 30% alpha-helix in 90% trifluoroethanol was characteristic of both. The peptide thus appears not to require the disulfide bridge to retain a looped conformation with amphipathic secondary structure. An essential positive charge at position 43 was shown by complete loss of activity upon substitution of Asp or Ala for the Arg found in all known species of LH. Other analogues showed a requirement for a neutral residue at position 47, also highly conserved.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of synthetic alpha-subunit peptides on thyroid-stimulating immunoglobulin activity

Synthetic peptides, representing specific portions of the alpha-subunit of the human glycoprotein hormones, can inhibit both the binding of labeled TSH to thyroid membranes and adenylate cyclase stimulation by TSH in vitro. The same synthetic peptides (alpha 26-46 and alpha 31-45) significantly (P less than 0.05) inhibited the adenylate cyclase-stimulating activity of thyroid-stimulating immunoglobulins (TSI) from 10 patients with hyperthyroid Graves' disease. Peptide alpha 26-46 was the most potent, resulting in 79.1 +/- 8.8% (+/- SE) inhibition at 133 micrograms/mL, while peptide alpha 31-45 inhibited TSI activity by 36.3 +/- 5.2%. Peptides alpha 61-75 and alpha 81-92, that had only minimal ability to inhibit TSH-mediated cAMP generation, did not significantly inhibit TSI activity. The inhibitory action of alpha 26-46 was dose dependent, and a significant negative correlation was found between the maximum TSI activity of the serum sample and the inhibition achieved by the synthetic peptide, suggesting that differences in TSI affinity and/or titer may account for the variable inhibitory activity of the peptides. These results suggest that TSI interact with the TSH receptor at the site that recognizes the portion of the TSH alpha-subunit represented by the synthetic peptide alpha 26-46 and, thus, support the concept that the TSH-binding site of the TSH receptor is the site of antigen binding between TSI and the thyroid cell.

The glycoprotein hormones: recent studies of structure-function relationships

The structural features of the heterodimeric glycoprotein hormones (LH, FSH, TSH, and hCG) are briefly reviewed. Removal of carbohydrate chains does not reduce binding of the hormones to membrane receptors, but markedly reduces biological responses. The glycopeptides from the hormone do not reduce binding of native hormone to receptors but do reduce biological responses. Newer data concerned with replication of different regions of the peptide chains of these molecules using synthetic peptides are reviewed and presented. These studies indicate that two regions on the common alpha subunit are involved with receptor binding of the LH, hCG, and TSH molecules. These regions are alpha 26 to 46 and alpha 75-92. Two synthetic disulfide loop peptides from the hCG beta subunit beta 38-57 and beta 93-100 also block binding of hCG to its receptor. In addition, the beta 38-57 peptide stimulates testosterone production by Leydig cells. These data indicate that glycoprotein hormone binding to plasma membrane receptors involves a discontinuous site on the hormone that spans both the alpha and beta subunits, and that the alpha subunit sites are similar for several hormones.

Replication of mitochondrial DNA in the gonadotropin-primed corpus luteum of the rat

The effect on mitochondria isolated from corpus luteal tissues following priming of immature female rats with pregnant mares serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) was studied. Ultrastructural studies showed intramitochondrial filamentous nucleic acid networks in situ following intense uranyl acetate staining. The intramitochondrial complexes were sensitive to nuclease treatment. Primed corpora lutea contained a 3.7-fold increase of mitochondrial DNA (mtDNA) per mg of mitochondrial protein when compared to unprimed ovaries. In subsequent experiments female rats were injected with 3H-thymidine 12 h before harvesting gonadotropin-primed corpora lutea from which mitochondria were isolated, purified and lysed. MtDNA was isolated and purified from the lysate by CsCl-ethidium bromide equilibrium buoyant density gradient centrifugation. Both the upper and lower bands of mtDNA as well as the intermediate region of the gradient contained radioactive label. When mtDNA from a fractionated gradient was mounted for electron microscopy and examined, replicative forms of mtDNA were observed. The mechanism of replication appears to be by the displacement-loop model of mtDNA replication. Ultrastructural as well as biochemical evidence indicate that a consequence of corpora lutea formation is the replication of mtDNA.

The effects of synthetic alpha-subunit peptides on thyrotropin interaction with its receptor

Synthetic peptides of the alpha-subunit of human glycoprotein hormones have been shown previously to inhibit binding of [125I]iodo-hCG to ovarian membranes, thus indicating the importance of the alpha-subunit in the structure-function relationships of the gonadotropic hormone. These same synthetic alpha-subunit peptides, the sequences of which are common to all human glycoprotein hormones, were found to inhibit the binding of [125I]iodo-TSH to human thyroid membrane preparations and FRTL-5 rat thyroid cells. The active portions of the subunit were represented in synthetic peptides alpha 21-35, alpha 31-45, alpha 26-46, and alpha 81-92, indicating that 2 separate sites within the alpha-subunit have binding activity for TSH. Peptides alpha 26-46 and alpha 31-45 were also found to potently inhibit the stimulation of adenylate cyclase activity by bovine TSH in TSH bioassay using FRTL-5 cells. Seven other synthetic peptides, including the remainder of the 92-amino acid sequence of the alpha-subunit, demonstrated little or no ability to inhibit binding of the tracer or inhibit the bioactivity of intact TSH. The findings were very similar to those of previous studies involving hCG binding, except that the two active sites appeared to be somewhat shifted towards the COOH-terminal end of the subunit. These studies support the concept of the importance of the alpha-subunit in receptor binding of all glycoprotein hormones and demonstrate the utility of the overlapping synthetic peptide strategy in investigations of protein structure-function relationships.

Follicle-stimulating hormone (FSH) immunoactivity in porcine follicular fluid is not pituitary FSH

Two inhibitors of FSH binding to receptor have been isolated from porcine follicular fluid and shown to have in vitro biological activity. These inhibitors were distinct separable entities with opposite biological effects (agonist and antagonist) on cultured FSH-responsive Sertoli cells. In light of the fact that the agonist-containing fraction (P4) inhibited [125I]human (h) FSH binding to anti-hFSH antiserum as well as to receptor, characterization of this factor was undertaken to determine its relationship to pituitary FSH. The P4 fraction was further purified by affinity chromatography, which removed a major protein from immunoreactive components. Western blotting of sodium dodecyl sulfate-polyacrylamide gels using polyclonal (anti-hFSH) and monoclonal (anti-hFSH beta) antibodies revealed a major immunoreactive band at 55,000 mol wt (Mr). When electrophoresed under reducing conditions, major immunoreactive proteins at 58,000 and 45,000 Mr were identified. These bands were also observed in extracts from bovine testes and raw porcine follicular fluid after electrophoresis and Western blotting. Whereas the monoclonal antibody used to characterize this inhibitor does not recognize porcine pituitary FSH, the Mr of the immunoreactive proteins are greater than that of pituitary FSH, and the immunoreactive bands do not reduce to subunits, as observed for pituitary FSH under reducing conditions, we conclude that gonadal extracts contain FSH-immunoreactive proteins that are immunologically and biochemically distinguishable from pituitary FSH. While the physiological role of these proteins remains to be determined, their presence in gonadal extracts or fluids vitiates assessment of FSH within the gonad by RIA using antiserum against hFSH.

The effect of deglycosylated human chorionic gonadotropin on corpora luteal function in healthy women

Fourteen healthy young women were studied through a control and a treatment menstrual cycle in two series of experiments. In the first series, they were given one of four doses of deglycosylated human chorionic gonadotropin (hCG) as a 24-hour infusion during the mid-luteal phase of the cycle. In these studies, there were no significant alterations of the length of the luteal phase of the treatment cycle, and there was no decrease in serum progesterone (P) during the infusion. In fact, serum P increased during the infusion. In the second series of studies, five subjects were given a 48-hour infusion of normal saline during the control cycle, and a 48-hour infusion of deglycosylated alpha-intact beta-hCG during the treatment cycle, both being administered during the mid-luteal phase. Treatment did not alter luteal phase duration and, again, increased serum P. It is concluded that deglycosylated preparations of hCG are not clinically useful as luteinizing hormone antagonists, probably because of residual agonist activity.

Inhibition of human choriotropin binding to receptor by human choriotropin alpha peptides. A comprehensive synthetic approach

Synthetic overlapping peptides of the alpha-subunit of human chorionic gonadotropin (hCG) were made by solid-phase peptide synthesis employing a comprehensive synthetic approach. The entire primary structure of the alpha-subunit was synthesized as a series of nine consecutive peptides, each 15 residues in length, and overlapping with its two adjacent neighbors by 5 residues on each side. Receptor binding activity of each synthetic peptide was measured by the inhibition of binding of 125I-labeled hCG to rat ovarian receptor. Peptides alpha 21-35, alpha 31-45, alpha 71-85, and alpha 81-92 were shown to compete for binding with native hCG, thus demonstrating that at least two regions on the alpha-subunit may be part of the binding site(s) of the hormone. The low affinity of the peptides (10(-5)-10(-6) M) compared to native hormone (10(-10) M) for receptor is not unexpected due to the probability of discontinuous and multiple sites involved in receptor binding. An ultrapure preparation of hCG alpha-subunit also had low affinity (10(-5), suggesting that conformational changes upon combination with beta-subunit to form dimer or changes in conformation after binding are necessary for high affinity interaction. These results correlate with previous predictions of binding sites based on studies employing chemical and enzymatic modifications of intact hormone and show that synthetic peptide strategies are helpful in the elucidation of protein structure and function.

Tryptophan fluorescence studies of subunit interaction and rotational dynamics of human luteinizing hormone

Human luteinizing hormone (hLH) has a single tryptophan residue occurring in the beta-subunit (beta hLH). This provides an intrinsic fluorescent probe, in native hLH and beta hLH, that is unambiguously assigned. The fluorescence intensities of hLH and beta hLH are, however, significantly different. This difference has been utilized in studying the interaction of fluorescent beta hLH with the nonfluorescent alpha-subunit. The accessibility of the tryptophan residue in native hLH and beta hLH has been assessed by measuring the rate of collisional fluorescence quenching and by solvent perturbation (D2O/H2O) of fluorescence. Fluorescence anisotropy measurements have been used in studying the intramolecular dynamics and segmental tryptophan mobility in hLH and beta hLH. Lifetime-resolved anisotropy, measured by the technique of oxygen quenching of fluorescence, has revealed the presence of segmental tryptophan motion. These data can be satisfactorily explained in terms of fast segmental tryptophan motion and rotational diffusion of the whole protein and do not require that intersubunit motion be invoked for intact hLH as it was suggested earlier on the basis of fluorescence depolarization of fluorescein-labeled hLH [Bishop, W. H., & Ryan, R. J. (1975) Biochem. Biophys. Res. Commun. 65, 1184-1190].

A receptor-binding region in human choriogonadotropin/lutropin beta subunit

Synthetic fragments have not been widely used thus far to evaluate structure-activity relations in the glycoprotein hormones. We prepared a series of peptides representing the intercysteine "loop" sequence (residues 38-57) in human choriogonadotropin (hCG) and lutropin (hLH) beta subunits, anticipating that it might be oriented toward the surface and accessible to receptors. The peptides were characterized chemically and tested for bioactivity by binding to rat ovarian membrane receptor and stimulation of Leydig cell testosterone production. The hCG beta-(38-57) and hLH beta-(38-57) peptides inhibited binding of 125I-labeled hCG half-maximally at 1.51 X 10(-4) and 2.03 X 10(-5) M, respectively, while other peptide hormones and fragments from elsewhere in the beta subunit were inactive. Both peptides stimulated testosterone production, with half-maximal responses at 3.55 X 10(-5) M (hCG) and 2.18 X 10(-5) M (hLH). By radioimmunoassay with an antibody to thyroglobulin-conjugated hCG beta-(38-57) peptide, native hCG and beta subunit were highly reactive, as were the reduced and carboxymethylated subunit and peptide. Helical-wheel projection predicted an amphipathic region in the N-terminal portion of the 38-57 sequence, and circular dichroic measurements showed an increase in ordered structure, especially alpha-helix, when the 38-57 peptides were transferred from an aqueous to a more lipophilic (90% trifluoroethanol) environment. These results indicate that the 38-57 region of beta subunit is exposed on the surface and constitutes a component in the receptor-binding domain for hCG and hLH. A region of amphipathic-helical structure in the 38-57 sequence may promote hormone-receptor interactions in a manner proposed for several other peptide hormones.

Electrophoretic analysis of membrane proteases in the luteinized rat ovary

Membrane fractions from fully luteinized rat ovaries contained proteolytic enzymes that were solubilized and reversibly inhibited by the anionic detergent sodium dodecyl sulfate. Electrophoretic analysis in substrate-containing sodium dodecyl sulfate-polyacrylamide slab gels revealed the presence of numerous protease bands in the mol wt range of 26,000 to more than 200,000. When casein served as protease substrate in the gels, enzyme bands of Mr 26,000, 28,000, 30,000, and 90,000 were produced by crude (2,000 X g pellet) ovarian membranes. Gels containing casein and plasminogen also revealed the presence of two plasminogen activators of Mr 63,000-65,000 and 42,000. Subcellular fractionation of luteinized ovaries by centrifugation in sucrose density gradients indicated that the Mr 90,000 protease and the two plasminogen activators were uniformly distributed among microvillous membranes, basolateral membranes (BLM), and the mitochondrial-lysosomal fraction (MLF). The Mr 26,000, 28,000, and 30,000 proteases were enriched in BLM and MLF. Analysis of crude membranes in slab gels which contained gelatin as the protease substrate revealed the presence of two additional enzymes of Mr 52,000 and more than 200,000. The Mr greater than 200,000 protease was present in microvillous membranes, BLM, and MLF. The Mr 52,000 protease was found exclusively in BLM. This enzyme was not consistently demonstrable in crude membranes but could be generated upon incubation of membranes at 30 C. This finding indicated that Mr 52,000 protease can exist in an inactive and/or zymogen form. The Mr 90,000 protease was inhibited by tosyl-lysine chloromethyl ketone and dansyl-glutamyl-glycylarginine chloromethyl ketone. The gelatinase activity of the Mr 52,000 protease was blocked by tosyl lysine chloromethyl ketone, dansyl-glutamyl-glycylarginine chloromethyl ketone and tosylamide-2-phenyl chloromethyl ketone. The activity of the Mr 26,000, 28,000, and 30,000 proteases was not affected by any of the above mentioned inhibitors. These findings demonstrate that the proteolytic potential of ovarian membranes is not limited to plasminogen activators. Numerous plasminogen-independent proteases are also present, and these may play a role in ovulation, luteolysis, and mediation of hormonal stimulation.