During the purification of the enzyme glycogen synthase from the muscle of the nematode Ascaris suum, approximately 70% of the glycogen synthase activity can be separated from the bulk of cellular glycogen by centrifugation for 60 min at 105,000 x . The glycogen synthase in the supernatant fraction has an Mr of 1.2 x 106 as determined by Sepharose 4B gel filtration chromatography. The glycogen synthase in this high molecular weight complex (glycogen primer complex) can be further purified by ConA-Sepharose affinity chromatography; the enzyme activity was eluted with 100 .mM a-methylmannoside. The glycogen synthase in glycogen'primer complex is predominately in the glucose 6-phosphatedependent form. The glycogen primer complex can catalyze the transfer of glucosyl units from UDP-glucose to an endogenous acceptor in the absence of exogenous glycogen. Analysis by SDS-PAGE showed three proteins (Mr 140,000, 78,000 and 34,000) and a carbohydrate polymer. The carbohydrate polymer can be partially digested with a-amylase. The glycogen primer complex was further digested by acid hydrolysis, and upon descending paper chromatography analysis, eight different carbohydrates were isolated, two of which were tentatively identified as glucose and sialic acid. The [14 C]-autoradiograph showed that in vitro synthesis of a glycogen-like polysaccharide occurred on this carbohydrate polymer. Polyclonal antibodies have been made to the glycogen primer complex, and Western Blot analysis indicated that all three proteins of the glycogen primer complex were antigenic. Collectively, the data indicate that a glycogen-like polysaccharide is synthesized from a carbohydrate-associated protein primer in the muscle of this worm.

No description available.

There is no abstract available for this dissertation. / Human Performance Laboratory

The purpose of this investigation was to determine the influence of post exercise carbohydrate (CHO) intake on the rate of muscle glycogen restorage after high intensity weight resistance exercise in untrained subjects. In a cross over design, eight male subjects performed sets (mean= 8.8) of 6 single leg knee extensions at 70% of one repletion max until 50% of full knee extension was no longer possible. Total force application was equated between trials using a strain gauge interfaced to a computer. Post exercise supplementation was administered at 0 and 1 hrs consisting of either a 23% CHO solution (1.5g•kg-1•hr-1) or an equal volume of water (H20). Total force production, pre-exercise muscle glycogen content, and degree of depletion (-40.6 and -44.3 mmol•kg-1) were not significantly different between H2O and CHO trials, respectively. During the initial 2 hrs recovery, the CHO trial had a significantly greater rate of muscle glycogen resynthesis as compared to the H2O trial. In the final 4 hrs of recovery no difference in repletion rates were observed. The glycogen content (mmol•kg-1 w.w.) and rates of restorage (mmol•kg-1 w.w.) during the recovery period were (mean + SE):TrialPost2 Hr6 HrRate (0-2 hrs)H2O101.3+ 13.1105.1+ 13.1105.5+ 13.01.3+ 2.2CHO91.7+ 11.8117.6+ 16.5123.4+ 15.1 *12.9+ 4.0*significance between trials, p <0.01Only the CHO supplementation trial restored pre-exercise muscle glycogen content after 6 hrs. The spectrophotometric analysis of glycogen stained muscle sections (PAS) indicated no difference between trials in the pre and post glycogen content for Type I and II fibers. The change in absorbance, when these samples were combined demonstrate greater glycogenolysis in the Type II (0.284 + 0.58) as compared to Type I (0.014 ± 0.076). During the recovery period, the change in absorbance supports greater glycogenesis in the Type II ( 0.096 + 0.060) when compared to no observed change in absorbance in the Type I fibers.Supported by a grant from Ross Laboratories. / Human Performance Laboratory

Glycogen synthase, the enzyme that catalyzes the rate-limiting reaction of glycogen syntheses has been purified and characterized from Ascaris suum muscle. Glycogen in the crude extract was digested to release the enzyme, eluted from a DE52 cellulose column and then applied to a Sepharose affinity column. The purified Ascaris enzyme was found to be homologous to the mammalian enzyme with regard to subunit and holoenzyme Mr^3 allosteric activation, substrate affinity and covalent modification. However, the association between Ascaris glycogen synthase and endogenous glycogen differed from that in mammalian systems.

A complex which synthesized glycogen de novo has been purifiedfrom Ascaris suum. This complex (GS-2) consists of a 66 KDa protein, a 140 KDa protein, and a>330 KDa glycoprotein.

Not available / text

Maintenance of adequate muscle glycogen stores has been shown to be essential for endurance performance. For athletes who train on successive days or twice in the same day it is especially important that feeding strategies result in optimal glycogen resynthesis between workouts. The purpose of this investigation was to determine if prior carbohydrate feedings and the form of the carbohydrate consumed affected subsequent endurance performance. Seven endurance trained male cyclists agreed to participate in this study. Each day of testing consisted of two exercise bouts. The first workout was an anaerobic workout consisting of five one minute efforts at 115% VO2max followed by a sprint ride to exhaustion. Each of the sprints was separated from the next by a four minute rest period. For the final ride, the subjects rode at 115% of VO2max. One hour following the completion of the first workout, the subjects began a feeding regimen in which one of four carbohydrate sources were ingested in an amount calculated to provide 1.5g carbohydrate/kg bodyweight/hr for the next four hours. The trials were grouped by carbohydrate forms, dense chewy solid (Powerbars) (DCS), liquid carbohydrate (Gatorlode) (LCHO), and semi-moist solid (Nabisco Snackwells and Fruit Newtons) (SMS). In addition, a water trial (W) was conducted to serve as a control The second workout occurred six hours after the completion of the anaerobic workout and consisted of a one-hour self-paced performance ride on a cycle ergometer. Performance was measured as work (U) performed during the ride. All carbohydrate forms (824.7±109.6 U) improved performance over water (782.0±121.7 U) (p<0.05). In addition, among the various carbohydrate forms, SMS (843.2±94.4 U) significantly improved performance over LCHO (807.3±141 U) and DCS (805.3±115 U) (p<0.05). Carbohydrate feedings between anaerobic and aerobic workouts in the same day improve performance. Also, the physical form of the carbohydrate influences performance. / School of Physical Education

The present study was designed to evaluate the influence of carbohydrate structure on muscle glycogen resynthesis. Eight college-aged male cyclists performed a depletion exercise protocol to decrease vastus lateralis glycogen concentration. This protocol consisted of 60 min of cycling at 75% V O2max, followed by 6 - one min sprints at 125 % V O2max, with a 1 min rest between each sprint. Following the depletion exercise, the subjects consumed - 3000 kcal over a 12 hour period, which was calculated to meet each subject's estimated daily energy expenditure. The carbohydrate (CHO), fat and protein content represented 65:20:15% of the calories consumed, respectively, and totaled 450 - 550 g of CHO. All of the CHO was derived from 1 of 4 solutions: 1) glucose, 2) maltodextrin (glucose polymer), 3) waxy starch (100% amylopectin), or 4) resistant starch (100% amylose). Muscle biopsies were taken after the depletion exercise protocol and 24 hours after the depletion protocol to determine glycogen concentrations. The postdepletion exercise glycogen concentration was similar in all 4 trials, and averaged 234.7 mmol/kg dry weight (d.w.) muscle. Twenty-four hours after exercise, the increase in muscle glycogen concentration was less in the resistant starch trial (90.8 f 12.8 mmol/kg d.w.) than in the glucose, maltodextrin and waxy starch trials, in which glycogen concentration increased 168.7 mmol/kg d.w. Following the 24 h post-depletion exercise biopsy, each subject performed a 30 min cycling time trial, so that the relationship between muscle glycogen concentration and performance could be examined. There were no differences in work output during the time trial or blood lactate concentration immediately following the time trial in any of the trials. In summary, glycogen resynthesis is attenuated following ingestion of carbohydrate with a high amylose content, relative to amylopectin or glucose; however, short duration performance at intensities < 75% VO2max is unaffected. / School of Physical Education

This study compared the exercise responses of a waxy starch (WS), resistant starch (RS), glucose (GL) and an artificially-sweetened placebo (PL) ingested prior to exercise. Ten college-age, male competitive cyclists completed four experimental protocols consisting of a 30 min isokinetic, self-paced performance ride preceded by 90 min of constant load cycling at 66% VO2max. Thirty min prior to exercise, they ingested 1 g•kg-1 body weight of GL, WS, RS, or PL. A familiarization trial was first conducted to eliminate a potential order effect. An order effect was evidenced by lower (p<0.05) work rates during the performance ride of the first trial (390 ± 26.1 kJ) than the other four trials. No order effect was observed for the remainder of the experimental treatments which were performed in a single-blind, randomized fashion. At rest, GL elicited greater (P<0.05) serum glucose and insulin responses than all other trials. During exercise, however, serum glucose and insulin responses were similar among trials. Blood C-peptide and glucagon responses were also similar among trials. The mean total carbohydrate oxidation rates (CHOox) were higher (p<0.05) during the GL, WS, and RS trials (2.59 ± 0.13, 2.49 ± 0.10, and 2.71 ± 0.15 g•min-1, respectively) compared to PL (2.35 ± 0.12 g•min-1). Subjects were able to complete more work (p<0.05) during the performance ride when they ingested GL (434 ± 25.2 kJ) or WS (428 ± 22.5 kJ) compared to PL (403 ± 35.1 kJ). They also tended to produce more work with RS ingestion (418 ± 31.4 kJ), although this did not reach statistical significance (p<0.09). These results indicate that pre-exercise CHO ingestion in the form of starch or glucose maintained higher rates of total carbohydrate oxidation during exercise and provided an ergogenic benefit during self-paced cycling. / Human Performance Laboratory